I02 



HOWELL. [Vol. IV. 



■marrow of very young kittens, about a week old, which had 

 been bled rather severely from the jugular vein some twenty- 

 four hours previously so as to increase the processes of blood 

 formation. The marrow was teased out quickly in an indifferent 

 solution of some kind upon a slide, the edges of the cover slip 

 were sealed with paraffin, and the slide was kept at a tempera- 

 ture of 37-38° C, by means of a warm stage. Various indif- 

 ferent solutions were tried, such as normal salt solution, am- 

 niotic liquid, aqueous humor, and blood serum ; but successful 

 experiments were obtained only when the serum of the same 

 animal was used as the teasing liquid. The other liquids were 

 given only one or two trials ; but as far as the experiments 

 went, they indicated that even such liquids as normal salt solu- 

 tion and amniotic liquid are sufficiently abnormal to cause a 

 suspension of the living activities of the nucleated red cor- 

 puscles. Two experiments were made with the animal's own 

 serum as the teasing liquid. In the first I saw two cases of 

 extrusion, in the second only one, in which I was able to 

 follow the process in part at least. In picking out the cor- 

 puscle to be observ^ed I found it was necessary to choose one 

 in which the nucleus already showed signs of extrusion, for 

 otherwise it would be impossible except by accident to select a 

 cell which had reached the proper stage. It was not difficult 

 to find a number of corpuscles with the nucleus beginning to 

 extrude. Many of them showed no further change, though 

 watched for some time ; but in three cases I was able to follow 

 the last stages of extrusion until the nucleus lay completely 

 outside of the cell. Sketches were made of one of these suc- 

 cessful cases, though unfortunately it was the most incomplete 

 of the three. The drawings are given in Fig. 2. The experi- 

 ments were discontinued because of the improbability of obtain- 

 ing a cell in which the process could be watched from the 

 beginning to the end. The results, as far as they went, were 

 still further proof to me that the extrusion of the nucleus is a 

 normal phenomenon, since it was obtained only when the con- 

 ditions were most favorable for preserving the life of the cell. 

 I have spoken of the escape of the nucleus as an extrusion, but 

 it is quite possible that migration would be a more accurate 

 term. I was not able to convince myself that the escaping 

 nucleus in the living cell showed definite amoeboid movements, 



