— 33 — 



defoliated stems. Hence, Leptobryum differs from the other 

 species already described in that the protonema production 

 is not called forth by defoliation. 



The form of branching of the protonema of Leptobryum 

 is worthy of note since it very frequently differs from the 

 ordinary mode of protonema branching 1 . In the normal branching 

 of protonema each cell is able to form a branch just behind 

 the cross septum. In this case however, two branches are 

 formed opposite each other and immediately behind the septum 

 (Fig. 48). The plants which I used for experiments were 

 grown in the green-house, and an examination of the sterile 

 plants showed that the production of protonema from the 

 leaf axile was quite general. The side branches of these 

 protonema often gave rise to strings of conidia-like cells, 

 which broke away from the branch bearing them. The cells 

 generally had assumed an oval form, were abundantly filled 

 with Chlorophyll bodies and quite often large oil drops and 

 besides possessed slightly thicker walls (Fig. 43, 44). The 

 striking similarity of this growth, to conidia formation in 

 fungi will at once be noted from the diagram. Some of 

 these conidia-like cells were placed in conditions favorable 

 for growth and after a lapse of about eight days germination 

 or growth had occurred as shown in Fig. 45. A great many 

 of the leaf axils, instead of giving rise to protonema or 

 rhizoids had produced dark brown, oval, multicellular brood- 

 bodies borne upon a stalk several cells long (Fig. 46, 47). 

 The rhizoids also gave rise to similar brood - bodies. The 

 conditions for this conidia production can not be stated. In 

 the artificial cultures when kept moist, this manner of breaking 

 up of the protonema branches into single cells did not occur. 

 The plants in the green-house were not however especially dry. 



PHÄSCUM CUSPIDATUM. 



The leaves of Phascum produced protonema with great 

 readiness and in less time than any other species investigated. 

 Cultures were made for both light and dark, part of the 



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