84 



THE AMEKICAN MONTHLY 



[May, 



resting period. Its further devel- 

 opment is unknown. 



The plant shown here has not re- 

 vealed the whole process of fructi- 

 fication as described by Reinsch. I 

 have not been so fortunate as to de- 

 tect the spermatozoids ; but, on the 

 other hand, I have seen what he 

 did not detect, the development of 

 the young plants from the spores. 

 The American plant I described as 

 " Hortnosjpora geminella^'' in the 

 Bulletin of the Torrey Botanical 

 Cluh, March, 187T ; the plant be- 

 longed to this genus, rather than to 

 any other of the older order of 

 classification. Now that the mode 

 of fructification and development 

 is known, it is evidently excluded 

 from that genus, and will be called 

 Cylindrocajpsa gemiiiella. 



Eeferring to the illustration, Fig. 

 17, yl is a filament in the normal 

 vegetative condition. Diameter 

 usually .0006", sometimes no more 

 than .0004"— .0005". B and C 

 are filaments with cells enlarging, 

 and developing spores. I) has cells 

 partly enlarged and others matured 

 into spores (.0008"— .001"), d, d, 

 are spores passing out of the oogo- 

 niums, ^represents the granular 

 chlorophyll of the spore, dividing 

 into four parts ; F, the parts en- 

 larging ; G shows further increase ; 

 and M, II, young filaments devel- 

 oped from them. 



Fkancis Wolle. 



About Diatoms. 



A correspondent expresses him- 

 self regarding diatoms in the fol- 

 lowing language, which will doubt- 

 less be interesting to many readers : 



" My difficulty is this : I see in 

 some gathering or slide, a diatom 

 that is new to me ; what is it ? I 

 know it to be, say a Wamcula, but 

 I would like also to know the rest 

 — Namicula what? I measure its 



length and draw its shape, and per- 

 haps the striation. Then I turn 



to the books and find ? Usually 



I find several species of Navicula^ 

 either of which Tnay be the one in 

 question. I find the size varies 

 considerably, the striation also 

 varies some, and the shape is often 

 very indefinitely described. My 

 specimen comes within the limits 

 of variation as to size and striation 

 of several different species — the 

 shape agrees with some and the 

 size and striations differ ; the size 

 agrees with some and the shape 

 and striation differ ; and finally the 

 striation comes within the limits of 

 several species, but the shape per- 

 haps differs from all — the result 

 is, complete uncertainty and disgust. 



" I believe the only safe plan to 

 escape insanity is to forswear dia- 

 toms forever, and stick to the iden- 

 tification of blood and to discri- 

 minating one kind from all others, 

 as affording the only field where it 

 is all plain sailing and no chance 

 for doubt or mistakes." 



Seriously, there is no doubt that 

 the difficulties which our correspon- 

 dent alludes to are not imaginary. 

 The study of the diatoms has long 

 been a favorite one, owing to the 

 beauty and symmetry of their forms, 

 the delicacy of their markings, and 

 their curious movements. Still, we 

 believe that it is seldom possible to 

 determine the species of diatoms 

 from descriptions alone. Typical 

 specimens or accurate drawings seem 

 to be necessary for the purpose. 



Soap for Imbedding. 



Dr. Heinrich Kadyl has con- 

 tributed an article to Zoologisch- 

 er Anzeiger entitled, " Soap as an 

 Imbedding Mass for the Prepara- 

 tion of Sections," and from a care- 

 ful reading of his paper we are in- 

 clined to the belief that soap is the 



