Luigi Galvani was a biologist who experimented on frogs in the 1780s. One day he was cutting a frog's leg and his scalpel came in contact with a metal instrument that was holding the leg. When that happened the leg twitched, leading Galvani to believe that he proved the existence of "animal electricity." Later experiments proved that Galvani was incorrect, and that the twitching just showed the presence of electricity between two metals.
The African clawed frog was the subject of an experiment by neurobiologist Roger Wolcott Sperry to show his Chemoaffinity Hypothesis. Sperry removed the eyes of the frog, rotated them 180 degrees and replaced them to see the effect on the frog's vision. The frog's nervous system repaired itself after surgery but the frog saw everything upside down. This showed that each optic fiber and tectal neuron had specific jobs no matter where they were. Sperry said they had cytochemical labels that were used to find their target cells. Because of this, the frog's vision was impaired.
Researcher Joseph Keisecker experimented with frogs to show the effects of pesticides. He found that pesticides lower a frog's resistance to parasites and these parasites cause deformities. Keisecker performed experiments in actual ponds: one was close to agricultural land and the other was far away. Tadpoles were introduced and monitored. He then experimented in the lab with three different kinds of pesticides at low and high levels. Low was the maximum permitted in drinking water and high was ten times that level. In the pond experiment there was a marked difference in abnormalities and the size of the frogs that were exposed was smaller. In the lab experiment, even the low level of pesticide lowered the immune system and the frogs had higher numbers of parasite-caused infections and deformities.
A fairly simple experiment was conducted by middle school students from Minnesota in 1995. They found out that half of the frogs in a pond had deformities whereas previously the average rate of malformation in a non-polluted pond was 0.2 percent. State officials were alerted which started evaluations of frogs in ponds all over the country. After five years of study, 44 states reported a high number of deformities among 38 species of frogs.