RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 27 



sary. The reproduction among Cryptogamia may probably often 

 exhibit phenomena analogous to the alternation of generation of 

 animals, but universally he thinks it will be discovered that a true 

 sexual mixture takes place in every species of these plants at some 

 period of their life. According to the observations of Schimper, it 

 is necessary among the mosses. From an observation made by 

 Klencke upon a fungus which grew upon a diseased surface, Dr. L. 

 thinks that sexual admixture would be discovered to take place in 

 the niyceliiDii. In numerous instances it had been observed among 

 the Algae. He stated he thought he had noticed the process in 

 Achyla prolifcra, and gave a description of the phenomena. He 

 finally considers that science is on the eve of demonstrating the 

 existence of a law " that an admixture of sexual elements is necessary 

 for the perpetuation of specific life germs.'" 



He then exhibited numerous elaborate drawings of new entophyta 

 observed growing in the ventriculus of Passalus cormttus, a remark- 

 able one growing in a honey-like liquid in the proventriculus of the 

 larva of Arctia Isabella, another from Acheta abbreviata, etc. He 

 remarked that when such plants were found in animals they were 

 usuall}' very abundant. 



Dr. L. then stated that very slight modifications in the five essen- 

 tial conditions of life were sufficient to produce the vast variety of 

 living beings upon the globe. As an instance, he mentioned he 

 had lying upon his table a saucer with a cork bottom, in which 

 lay a partially dissected Passalus cornutus half immersed in water. 

 Two days afterwards he noticed upon the part of the insect above 

 the water a quantity of Mucor mucedo {f) growing, and from the part 

 within the water numerous fine, stiff filaments, which upon exami- 

 nation proved to be Achyla prolifera ; upon the cork around the 

 insect grew a third genus, consisting of fine cottony filaments, which 

 were articulated, of which he exhibited a drawing ; and upon the 

 insect at the surface of the water, but not within the latter, grew a 

 fourth genus, of which he also exhibited a drawing. 



He also stated that he had had the good fortune of observing in a 

 single morning all the stages of development of Achyla prolifera 

 growing from some individuals of Ascarides which had been lying 

 in a dish of water for a few days. 



In reply to some remarks made by members. Dr. L,eidy said he 

 could not admit the doctrine of spontaneous generation, but rather 

 thought modifications in the essential conditions of life favorable to 

 the development of different and always pre-existing germs derived 

 from a parent. 



