RESEARCH ON THE DIGESTIVE SYSTEM OF THE SCHIZOPODA 1 3 



Yet with ail the solutions, and in spite of every précaution, there is 

 always some shrinkage of the epithelium, which thus becomes separated 

 from the chitinous cuticle, as will be seen from our drawings. 



Methods of embedding. 



If the animais hâve been eut beforehand, as we hâve described above, 

 the paraflîn pénétrâtes readily enough into the tissues, provided that the 

 larger animais are left in the mixture of chloroform and parafifin from 3 to 

 4 hours, and for 1 hour in paraffin alone. 



The fixing by means of the nitrate of copper solution hardens the tis- 

 sues. If this solution is used for hxing, the pièces must be left for 6 hours 

 in the mixture of chloroform and paraffin, and for 2 hours in the paraffin. 



We hâve also made use of coUodium for embedding, with great advant- 

 age, in the case of the larger animais, although the sections are not so fine as 

 those obtained with the paraffin method. The rapid method of Professor 

 GiLSON has given excellent results. We give the time employed in the dif- 

 férent stages after dehydration : 



Mixture of alcohol and ether jo minutes. 

 Thin solution of collodium 8 hours. 



Washing in a mixture of alcohol and ether 1 minute. 



Hardening in a small quantity of chloroform 30 seconds. 



Melted paraffin is then added to the chloroform and carefully wartned, 

 till the chloroform has completely evaporated, This generally occupies 

 about lô minutes. The pièces are then left in melted paraffin for another 

 15 minutes. 



There is a great economy of time in boiling the pièces in a thin solu- 

 tion of collodium during 45 minutes. The' pièces are then hardened and 

 transferred to the paraffin as indicated above. 



Methods of stainiug. 



We hâve always coloured our sections on the slides. Pièces stained en 

 masse are not uniformly coloured, the chitinous cuticle preventing the 

 stains from penetrating to the innermost tissues with sufficient rapidity. 

 We hâve made use of Delafields hsematoxylin solution followed by the 

 acid alcohol u'ash, the alum carminé solution of Mayer, paracarmine and 

 acid fuchsin. 



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