59 



from the incubator and examined, when the process of moulting 

 had still further advanced. At 4 p. m., I found them all dead. 

 The culture fluid had become putrid. 



Exp. 21. May 7th, 4 p. m. Completely satisfied that I was on 

 the right track, I removed four more embryos from an earth- 

 worm and placed them in another portion of serum, and in the 

 incubator as before. On May 8th, at 9 a. m., removed them to 

 another watch glass containing fresh serum, by taking them up 

 under an inch objective with a small splinter of wood whittled 

 to a fine point. At 9 p. m. the same day, they were again re- 

 moved to fresh serum. One was found dead, another had 

 molted, and the two others had nearly completed that process. 

 May 9th, 9 a. m. They were seen to have increased in size, and 

 were removed to another portion of serum. These embryos 

 lived between four and five days in the incubator, and were 

 about moulting the second time. I think they were sufficiently 

 developed to show that they were the embryos of syngamus. 

 One of them measured about .0139 inch in length, and the exu- 

 viae, in which it still remained, about .0227 of an inch. 



Exp. 22. Four of the embryos from the earthworm were 

 placed in one drachm of egg albumen, after it was beaten to 

 render it fluid. They were placed in the incubator as before, 

 and changed to fresh albumen daily. After being kept in this 

 way six and one-half days, they were alive, but there was no 

 change in their structure or size, or any appearance of moulting 

 perceptible. Evidently, the proper food for their metamorpho- 

 sis and growth was not contained in this fluid. In these culture 

 experiments the incubator used was one in which the heat could 

 not be thoroughly controlled. It is believed, with a good one 

 and more experience, better results could be attained. It is also 

 thought the blood serum of a fowl would be the best adapted 

 for this purpose. 



This method of artificial culture of animal parasites is believed 

 to be new, and if varied according to the different circumstances 

 in which they are found in nature will, we think, render easy the 

 solution of some of the most difficult questions, as to the life 



