12 Charles GELDERD 



The material for study was collectée! by Professor Gilson during his 

 voyages of exploration in the North Sea. 



METHODS. 



We hâve made sections in our animais in différent directions, vertical, 

 transverse, horizontal and oblique. By this means only, is it possible to 

 obtain a précise knowledge of the positions of the stomach pièces in the 

 cavity, and their relations to one another. 



Methods offixing. 



Many of our animais hâve been fixed in a mixture of formaline and 

 alcohol with the following percentage of each : 



Commercial formaline at 40 % 5 ce. 



Alcohol at 94 % 30 ce. 



Distilled water 100 ce. 



They hâve given good results for anatomical study. 



If whole animais are put into the fixing solution, it does not penetrate 

 the integument as quickly as is desired, on account of its chitinous nature. 

 We hâve, therefore, always divided our animais and fixed the thorax and 

 pleon separately. If this is done, the fluids easily penetrate into the tis- 

 sues, and there is no need to decalcify the integument. 



It is useful also to eut off the antennœ, to facilitate the entrance of the 

 liquid into the head part. 



The nitrate of copper solution of Professor Gilson has proved an ex- 

 cellent means offixing Crustacea. We give the formula of this solution : 



Nitrate of copper 200 gr. 



Commercial formaline 500 ce. 



Sea water 200 ce. 



7 ce. of the above are used with 100 ce. of sea water. 



By the employment of this mixture, ail the organs remain in their 

 natural positions, which is of great importance in the case of the stomach 

 pièces. There is very little shrinkage of the epithelium. We hâve also used 

 the solutions of Boum, Hermann and Flemming, which hâve fui-nished 

 ail that could be desired for the study of histology and cytolog}^. 



