14 Charles GELDERD 



The best stain for our animais has proved to be that of alum carminé 

 combined with blue carminé, followed by a rapid washing in a feeble 

 solution of picric acid in alcohol. 



This method is somewhat long, but it is well worth the trouble, for it 

 brings out with great clearness, the various histological structures. The 

 muscles are coloured with a greenish blue; the chitinous cuticule, so im- 

 portant to distinguish in the stomach pièces is of a grey tint. The nuclei 

 are red. 



For the study of histology and cytology, we bave employed the hîe- 

 matoxylin solution of Heidenhain and the wash in the ammonium sulphate 

 of iron solution, followed by a slight tint of Congo red. 



After staining, the préparations are mounted with Canada balsam, or 

 with the euparal of Professer Gilson which has the great advantage of 

 being able to be used after dehydrating in 70 % alcohol. 



Isobutyl alcohol has been found to be of the greatest utility when 

 euparal is employed for mounting. It is much less volatile than ethyl 

 alcohol, and absorbs water with much less rapidity. An extremely délicate 

 dehydration may be obtained where difficult objects are to be mounted. In 

 the employment of absolute ethyl alcohol, which has a great avidity for 

 water, there is always a danger of contracting the tissues, This is avoided 

 if isobutyl alcohol be used, and there is no danger of the operator's breath 

 spoiling the préparation. The method of procédure is the following : 



Dehydrate with ethyl alcohol at 70 "/o- 

 Wash in isobutyl alcohol. 

 Mount immediately with euparal. 



There is therefore an immense saving of time and labour. 



It is préférable, however, not to use isobutyl alcohol when the prépa- 

 rations hâve been coloured with the aniline stains, as a diffusion of the 

 colouring matter is produced. 



