20() 



k'uriicd liow ini|)uil;inl llu' condilioii of Ihc m i 1 i t- u c x- 

 Irririirc is lor llu'sc proct-sst's. Jii llic milieu i ii I r i* i- 

 eure i. e tlic pfoloplasiiKi in llu- organism as a whole, 

 we have llic tlu-alrc loi" j)i'occsses oT Ihc {^realcsl imporlancc, 

 but very (lirncull to lacklc hy cxix-i-imcnlal investijfalion al 

 the present lime. Frohably Ihe many products, that we call 

 internal secretions are lransi)orted directly from proloplasma 

 to protoplasma by means of the cellular anaslomotics. This 

 is as yet unknown. 



4. M()RPil()(ih:.\KTICS. 



The nielhod of cultivating^ tissues outside the body has 

 mainly been employed for the study of the in()r|)hology 

 of tissue cells. Seen from the point of view of Ihe morpho- 

 logisls, the technique of explantalion of tissue cells is a 

 convenient method for the study of the structure of the 

 various cells. 



Preparation of living tissue cells on a coverglass have, of 

 course, gi'eater advantages than the ordinary histological 

 methods The cells can be observed in a condition of actual 

 life for long j>eriods of time under various experinu'ntal 

 ctmditions. At any time the life of the cells may be inter- 

 rupted and beautiful specimens made of the cultures, and 

 the same cells observed during life can now be studied in 

 the i)ermanent preparation. The methods which the morpho- 

 logisls use for explantalion, usually allow the tissue cells 

 to grow out on the cover glass in a unicellular layer, and 

 this gives stained and permanent preparations unsurpassed 

 in l)eauty. 



The methods of tissue explantalion have also disadvanta- 

 ges in the hands of the morphologists. Very often the mor- 

 phologists are not physiologists enough to avoid conditions 

 which are loo artificial and eriX)neous conclusions are easily 

 drawn. The methods generally employed by the morpholo- 

 gists are to be considered as conditions of survival rather 

 than cultures, according to Carrel's definition. This con- 



