202 Nichols, A morphological study of Juniperus communis var. depressa. 



writer's results withthose of Noren that the cytological phenomena 

 in the American variety resemble in most important respects those 

 in the European form. 



Collections of material were made near New Haven, Connecti- 

 cut during the years 1906, 1907, and 1908. The frequency of 

 collections and the manner of treating the material varied somewhat. 

 Staminate cones and first year ovules were collected at intervals 

 of from two days to a week and placed directly in the killing fluid. 

 The younger second year ovules were collected every one or two 

 days and split lengthwise with a sharp knife before treating with 

 reagents. After the development of a firm integument it was found 

 necessary to carefully dissect out the nucellus before immersing it 

 in the killing fluid. Collections were made daily after the appearance 

 of archegonia. In the later stages material was killed and fixed 

 in the field, bat in the earlier stages this was usually done in the 

 laboratory. Material brought indoors and kept in water for not 

 more than a week appears to develop normally. Various killing 

 and fixing Solutions were tried, and excellent results were obtained 

 with the modification of Flemming's chrom-acet-osmic fluid re- 

 commended by Mottier (1897). The writer expresses his thanks 

 to Prof. Alexander W. Evans, atwhose Suggestion this work was 

 undertakem, for his helpful criticism and kind advice. 



The microsporangium. 



Development of the microspore mother cells. — Hof- 

 meister (1848) describes the microsporangium of Pinus maritima 

 as being in the spore mother cell condition in November, and this 

 seems to be the first published reference to the development of 

 this structure among the Gymnosperms. Groebel (1881) makes 

 several observations in regard to the development of the 

 microsporangia in this group, and in Pinus traces back the 

 archesporium to a Single hypodermal cell. In Thuja (Biota), which 

 he cites as typical of the Cupresseae, he finds that the archesporium 

 is likewise of hypodermal origin, but whether it arises from one 

 or several cells he does not make out. He also makes the State- 

 ment, later upheld by Coulter and Chamberlain (1901) and 

 other recent writers, that in all important respects the development 

 of the microsporangium in the Gymnosperms follows the same course 

 as in the eusporangiate pteridophytes. In the cycad Stangeria 

 Lang (1897) finds that the sporogenous cells "are derived by 

 periclinal division from cells of the sub-epidermal layer". A similar 

 origin is reported by Coker (1903b) in Taxodium, and Coulter 

 and Land (1905) are of the opinion that in Torreya the arche- 

 sporium arises from a hypodermal cell. 



The staminate cones of Juniperus communis var. depressa 

 become recognizable late in the summer and pass the winter in a 

 more or less rudimentary condition. In material collected No- 

 vember 28 th it is in most cases impossible to distinguish vegetative 

 leaves from sporophylls, and many of the latter do not begin to 



