i5 



gamus, and later in the investigation were fully identified as being 

 the same. 



Exp. 19. Placed several embryos from the intestinal canal of 

 the earthworm, like those in the preceding- experiment, in a cov- 

 ered glass dish of water, and then in an incubator, and kept them 

 at 105 Fahrenheit for seven days, at which time they were alive, 

 but no change of structure or development had taken place. 



Exp. 20. One pint of blood from a calf was allowed to stand 

 in a glass fruit jar until the solid portion had settled, leaving the 

 serum at the top. On May 5th, at 9 a. m., one dram of this 

 serum was placed in a Syracuse solid watch glass, with ground 

 edges, containing twenty of the last described embryos. These 

 embryos had been kept in the watch glass in water one week, 

 and were nearly all lying quietly coiled up about its center. The 

 most of the water was removed by a pipette before the serum 

 was added. As soon as this was done the embryos uncoiled 

 and became quite lively, as though they had at last found their 

 natural element. The watch glass was placed in an incubator, 

 covered by another one with ground edges, but leaving a small 

 space for air. The temperature had previously been regulated 

 so as to remain at 105 Fahr. At 9 p. m., on examining them 

 with the microscope, they had slightly increased in size and were 

 commencing to moult. On May 6th, at 9 a. m., they were again 

 taken 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 removed 

 to fresh serum. One was found dead, another had moulted, 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. They were sufficiently developed to show the peculiar 

 structure of the mouth of Syngamus trachealis. One of them 



