Techniques of Colchicine Treatment 377 



biopsy;^^' ^^ this is one ot the methods for treating human tumors 

 with the alkaloid, prepared in a vaseline-lanoline paste (Chapter 

 10) .If'- ^ Local applications of colchicine-im])res;nated agar cut into 

 small fragments have also proved useful in studying the origin of col- 

 chicine malformations in eggs;^" this technique does not seem to have 

 received the attention it deserves. 



Another method by which colchicine is brought into direct con- 

 tact with the cells is the use of the so-called "ascites-tumors" in mice. 

 These are neoplasms freely growing in fluid gathered in the ab- 

 dominal cavity. Colchicine is injected intraperitoneally, and re- 

 peated observations of the cells are possible by removing a small 

 amount of the ascites fluid. *- 



j6A.^-2: In vitro techniques. For many studies, it is preferable 

 to keep precise amounts of colchicine in contact with the cells which 

 are studied. This enables the results not to be disturbed by general 

 toxicity reactions and other pharmacological side-effects of colchicine 

 (Chapter 7) . More concentrated solutions may be tested, which, in- 

 jected to ^vhole animals, would have brought death through nervous 

 and respiratory paralysis. These techniques apply especially to warm- 

 blooded animals. 



In invertebrates, however, some remarkable results, discussed in 

 Chapters 2 and 3, have been obtained by the study at 38°C. of the 

 isolated nervous system of the grasshopper, Chortophaga viridifas- 

 ciata De Geer. Embryos, at an age equivalent to 14 days' development 

 at 26°C., are removed from the egg in artificial culture medium. The 

 maxillary and thoracic appendages, the head, and the posterior half 

 of the abdomen are discarded, and the embryo is mounted ^vith the 

 ventral nervous system close to a cover slip, which is sealed. These 

 hanging-drop preparations may be observed for several hours under 

 oil-immersion objectives'^' ^i (cf. Chapter 3, and Fig. 3.1). This has 

 proved to be one of the most interesting techniques for the study of 

 the spindle destruction by colchicine and of the mitotic cycle. '^ Iso- 

 lated eggs of invertebrates, for instance Arbacia,^ should also be men- 

 tioned here, although the techniques do not differ from those used in 

 experimental embryology (cf. Fig. 3.3 and Chapter 8) . 



In mammals, two tissues have provided excellent material for the 

 study of mitosis in x'itro. Fragments of the ear of mice may be in- 

 cubated in AVarburg flasks, and the action of various chemicals on 

 mitotic growth studied on the epithelium, the mitoses of ^vliidi ])er- 

 sist for several hovns, provided that glucose is added to the medium. '^ 

 Bone marrow is readily available in many mammals, including man, 

 and its mitoses may most simply be observed in cover-slip prepara- 

 tions at 37°C. Glucose does not appear to be as necessary as for 

 epidermal cells.- This technique has provided most useful data on 



