1902.] NATURAL SCIENCES OF PHILADELPHIA, 303 



testiue fixed iu Hermauu's without acetic, I fouud the alveoles well 

 preserved (figs. 11, A, 12, etc.).*^ 



Two obstacles appear to stand iu the way of recoguiziug the alve- 

 olar structure by ordinary methods. Iu the first place, the iuter- 

 alveolar substance, concerning which more will be said later, precipi- 

 tates in the form of granules iu the interstices between the alveoles, 

 so as to look much lib: the nodes of a reticulum. In the second 

 place, the contents of the alveoles precipitate also as fine granules on 

 the alveolar walls. So that after sublimate-acetic fixation, for 

 instancfs the effect is precisely Avhat one Avould expect from a retic- 

 ular structure. The best conditions, therefore, for observing the 

 true cytoplasmic structure would be where the interalveolar substance 

 is less abundant, and the contents of the alveoles is slightly or not 

 at all precipitated. Fig. 6 represents such a place ; Fig. 7, A, is 

 also favorable in places (e. g., centre near the top). Iu the former 

 figure the alveoles are represented by continuous Hues as they should 

 he ; but for representing the combined effect of alveoles and granular 

 substance, it has been necessary iu the interest of simple drawings 

 to adopt the conventional method seen in all the other figures. In 

 fig. 6 it will be seen that the fibres have a very definite relation to 

 the alveoles ; often in this intestine, and in many others, the alve- 

 oles are plainly between fibres, and the fibres between alveoles as 

 represented. This structure is easily seen in the free ends of the 

 median cells of a fresh intestine mounted iu blood. It is easy to 

 understand how Ide and later writers should have mistaken this 

 arrangement for the reticular, and should have supposed that the 

 fibres are joined by trabeculse. Ide seems to have recognized the 

 independence of the fibres, where he says: "If it were shown that 



^The fluid was suggested to me by Misses Foote aud Strobel (19), who 

 were able to preserve the alveolar structure (hyaline globules) of the 

 eggs of Allobophora foetida in it much better than in any other fluid. 

 Their photographs of the living egg aud of the structure' as preserved 

 by this tixation, which I have been permitted to see, are very convinc- 

 ing. Use had been made of this fluid to some extent early in the study, 

 but as the nucleus appeared not to be so well preserved as with other 

 fluids, it was set aside temporarily ; more recently it was eniploved 

 throughout a series of physiological stages, with results far more satis- 

 factin-y for many purposes than were obtained with any otiier fluid. 

 However, the alveolar structure has been met, occasionally very well 

 preserved, after Hermann's, Flemming's, picro-formalin, and sublimate 

 acetic (fig. 10, B). Ordinarily with these and all otht'r fluids, except 

 tlie platinic-chloride and osmic acid mixture, the structure appears to lie 

 reticular. 



