80 THE JOURNAL OF BOTANY 
protoplast divided. With very few exceptions the protoplast 
divided only once, so that only ee young individuals (embryos) 
arose from each zygos . (fig. 4, D-G). In a few cases, but 
certainly not in 2 per cent. of the eens dena was a second 
Fie —A-C, conjugation of Mesotenium caldariorum, C being the 
comple ae “zygospore. D-I, ging of zygospore. D-G, the usual 
ge sel operas ith the formation of t mbryos. H and I, the exceptional 
germination with formation of four aenbeve: All x 460. 
The foregoing observations on the cell-division and germina- 
tion of the zygospore of Mesotenium caldariorum are of particular 
interest in view of the attempt by Oltmanns* to establish within 
the Conjugate a third family, viz. the Mesoteniaceze. He sub- 
divided the Conjugatze into the three families of the Mesoteniacez, 
ygnemacee and Desmidiacew. After acquiring a singularly 
seins knowledge of the Desmidiacex, this is a view to which 
I cannot subscribe, and the late Dr. Liitkemiiller, of Vienna, who 
had studied the morphological detail of European Desmids very 
ee informed m s letters that he could not 
support Oltmanns’ a ‘The family Mesotzeniacez of Oltmanns 
is precisely soruye alent to the sub-family Spirotenie of Litke- 
miuller,t and the removal of these undoubted Desmids from the 
family Desmidiacez seems to me to be contrary to their affinities. 
oa Oltmanns, Morphologie und reeecard der Algen, Jena, 1904 
+ J. Liitkemiiller, ‘‘ Die Zellmem der Desmidiaceen,” Cohn’ s Beitriige 
zur Biologie der Pflanzen, viii, 1902. 
