LAZZARO SPALLANZANI: BIOGRAPHY, EXPERIMENTS - BIOLOGY - 2025

Lazzaro Spallanzani, born in Scandiano, Italy, on January 12, 1729, was a naturalistic intellectual who stood out for his studies, research and teaching in multiple areas, such as biology, physics, metaphysics, mathematics, logic and Greek, in addition of being also a catholic priest.

Initially his academic training was influenced by the likes of his father, a lawyer who wanted his son to continue on the same path. Spallanzani, with no intention of contradicting himself but with contrary interests, developed within the scientific sphere, this time inspired by his cousin Laura Bassi.

When his father granted him permission to abandon his law studies at the University of Bologna, he received sacred teachings and became a priest, at the same time that he taught classes in logic, metaphysics and Greek at the Jesuit college in Reggio.

His studies in science were learned at the University of Modena and at the University of Pavia, where he enrolled as a professor of Physics. In these same institutions he carried out most of his research and also taught lessons in philosophy, physics, and natural history. He also directed the mineralogical museum of Pavia.

At the early age of 25, Spallanzani stood out in every field that interested him and was capable of handling various tasks in any academic field. For example, he could translate works of classical poets, write articles on mechanics, and create debates and complex lines of mathematical questions.

Experiments

Spontaneous generation

One of the most recognized studies of this Italian scientist was his research on the theory of spontaneous generation, which raises the emergence of animals and plants through organic and / or inorganic matter, with body parts of amphibian and reptile animals, an idea adopted from the Italian physician and naturalist Francesco Redi.

Its main objective was to explain why this same emergence did not occur with humans and other animal species. Although his conclusions were not completely decisive and straightforward, at least it paved the way for new studies that followed the same guidelines, as did the French chemist and bacteriologist Louis Pasteur.

Biological controversies

The publication of works and essays such as Essay on Animal Reproduction, Booklets on Animal and Plant Physics and Essay on Microscopic Observations demonstrated his opposition to the theory of spontaneous generation, in which he also disagreed and criticized the research of the English biologist John Turberville Needham and the French naturalist Buffon.

The discrepancy between the two thoughts was one of the most controversial issues in 18th century biology, since in a second attempt and following the same experiments by Needham and Buffon, Spallanzani demonstrated that organisms, including microscopic ones, arise from existing ones.

The conclusion was obtained from a detail that the English and French omitted: the closure of the study jars was not enough with wooden or cotton caps, since in the same way the outside air enters and new microorganisms arrive.

This theoretical basis was the criterion used later by Pasteur and with which he obtained success in his research.

Natural and artificial fertilization

Another of the studies carried out by this Italian naturalist was the observation and analysis of human and animal reproduction, starting with understanding the natural process of fertilization to later carry out artificial insemination tests.

With a believing tendency towards the preformist and Ovista theory, which states that the growth of an embryo is given by an existing organism, Spallanzani's objective was to experiment with the reproduction of different animal species.

In a first phase, he studied the fertilization process with the frogs and concluded that it had to be produced externally.

For the next phase, he used the virgin eggs of the frogs from the first phase to put them in contact with seminal fluid and thus achieve fertilization. With detailed monitoring of the process, Spallanzani managed to conclude the first artificial insemination work with the hatching of the larvae.

The continuation of the study of artificial fertilization was carried out with tests on a pair of dogs. For this he made an injection of sperm in the female and she became pregnant.

Although initially Spallanzani's idea about sperm was that it was some kind of parasite, the conclusions of this experiment demonstrated the importance of these in fertilization and how with only a small portion, the reproduction of life can begin.

These experiments were a great step towards understanding the genesis of animal, plant and human life. Likewise, he suppressed the theory of aura seminalis, which stated that the growth of an egg occurred through a vapor that released the seminal fluid and not through contact.

Digestion process

The vast scientific subjects that Spallanzani tackled gave him the reputation of being the "biologist of biologists", because he also studied - and it was one of his great passions - the process of digestion.

The aim of this new experiment was based on the demonstration of the similarity in the human and animal digestive process. For this he used himself as a test in the tests and ingested a canvas sack containing 4.5 kilograms of chewed bread. After 23 hours, his body expelled the empty canvas sack through his anus.

Their conclusions, in a general way, were that the gastric juices that are part of digestion are acidic, which means that they are involved in a chemical and not mechanical process, as used to be believed until now.

Second stage

In his eagerness to indulge his scientific curiosity, Spallanzani proceeded to continue the study of digestion, but with greater ambitions.

He then went on to ingest tiny metal tubes and wooden spheres covered with gauze and filled with assorted foods and then tried unsuccessfully to vomit them up.

Criticisms of this research were immediate and one of these came from the English surgeon John Hunter, who in his experiments raised the idea that digestion occurred properly in the stomach with the help of gastric juices from the interior.

Another criticism was issued by the French intellectual Voltaire. Even so, Spallanzani continued his natural projects.

Echolocation of bats

Animal study was one of Spallanzani's staples. However, so far he had not tested others other than reptiles.

The next step was the tests with bats, especially since he noticed that these nocturnal mammals always find their way in the dark, and he established differences in cases such as owls, also nocturnal birds.

To begin with, Spallanzani caught several bats from Pavia's cathedral, blindfolded them and proceeded to release them. Days later, he observed that they had not lost the ability to do their eating and housing routine.

The next step was to predict that the sense of hearing was what gives them orientation in the dark. To check it, he captured them again, but this time he covered their ears. Thus, he saw them disoriented and how they collided with the objects that they found in their path.

These conclusions were decisive and were later complemented with new experiments that helped to specify more in the echolocation of these birds.

Insects, human respiration and volcanoes

The use of insects to verify new studies was a characteristic that Spallanzani inherited from the Italian physician and naturalist Antonio Vallisneri, who was also his tutor.

Spallanzani tested flies, silkworms and caterpillars for heat tolerance, concluding that their maximum lethal temperature is 37.5 and 43.5 ° C.

On the other hand, human respiration was a testing center for the scientist, trying to demonstrate how inhaled oxygen is transformed into exhaled carbon dioxide. Similarly, for this experiment, he used insects such as larvae, pupae and adults, lepidoptera, bees and wasps.

As the Italian's experiments were always so varied, he also undertook research projects on volcanoes, for which he made trips for direct observation of them, including Etna, located on the east coast of Sicily, Italy.

He also visited Asia Minor, Campania, Stromboli, the Lipai Islands and the Aeolian and Apennine Islands of Modena, with the aim of collecting volcanic rocks and minerals for the Natural History Museum of Pavia.

The experience was described in his work called Journey to the Two Sicilies and some parts of the Apennines, published between 1792 and 1797.

Finally, Lazzaro Spallanzani died on February 11, 1799, in Pavia, Italy, due to a stroke.

References

1. Elizabeth Belmont Gasking (2008). Lazzaro Spallanzani. Taken from britannica.com.
2. Juan Antonio Barcat (2009). Lazzaro Spallanzani and artificial insemination. Taken from scielo.org.ar.
3. Nuria Martínez Medina (2010). Lazzaro Spallanzani, "biologist of biologists." Taken from rtve.es.
4. Ecured (2018). Lazzaro Spallanzani. Taken from ecured.cu.
5. Biographies and Lives (2004-2018). Taken from biogramasyvidas.com.
6. M. Macho (2014). Lazzaro Spallanzani, "biologist of biologists." Taken from ztfnews.worpress.com.
7. Wikipedia (2018). Lazzaro Spallanzani. Taken from wikipedia.com.