2'2G H. GRAHAM CANNON 



of this he states : ' ist einmal die Granularfiirlmiig eiiigetroten, 

 so bleibt sie auch konstant, das Bild derselben ilndert sich in 

 keiner Weise, wie lange auch die Tiere beoljachlet werden 

 mogen. Und was ebenso wichtig ist.. farbt man eine grossere 

 Anzahl von Tieren, so weisen Zellen der gleichen Art stets auch 

 die gleichc Granuherungsart auf '. In the experiments on 

 Siniocephalus vetulus no such constancy was observed 

 in the labral glands. While these remained stained they did 

 not continually present the same appearance ; moreover, not 

 only did the glands of different individuals stain different!}'', 

 but the glands of the different sides of the same individual 

 stained differently, which is what one would expect from the 

 mobile, vacuolated nature of the protoplasm constituting the 

 labral glands. However, quite apart from this case, this con- 

 stancy in the appearance of a cell stained intra vitam with 

 neutral red does not agree with the fact that by such staining 

 methods the mitoclirondria are stained (Gatenby (7)). Lewis 

 and Lewis (11) have shown that not only do mitochondria 

 continually change their shape but also are continually shifting 

 their position. 



If specimens are fixed in sublimate after staining intra 

 vitam with neutral red and dehydrated rapidly some of the 

 stain remains in the specimen. If they are now embedded 

 and sectioned, on mounting the ribbon the stain can be seen 

 in patches in the labral gland, and the position and shape of 

 these can Ije drawn with reference to the contour of the glands. 

 If now the wax is removed and the sections brought down to 

 water the remaining stain is washed out. Staining now with 

 an aqueous solution of thionin there appear dark bodies in 

 the section staining an intense violet, almost black, and these 

 patches agree with those stained by the neutral red. In sections 

 of the animals which have not been stained with neutral red 

 but which had been similarly fixed and stained in thionin, 

 these very conspicuous dark bodies do not occur, and it seems 

 safe to assume that they are formed by the action of the neutral 

 red on the animal. 



Weak solutions of neutral red apparently always have a harm- 



