270 Transactions. 



remarkable variations of it. In two or three instances old pro- 

 thalli attached to young plants were very similar in appearance 

 to those of L. cernuum shown in figs. 18 and 21. The other pro- 

 thalli, however, were either long-drawn-out, being from 2^- mm. to 

 4 mm. in length, or short and comparatively massive. Eighteen prothalli 

 of the former kind were found, two of which bore very young plants. 

 Three of these are shown in figs. 32b, 32c, and 32d. Of the latter kind 

 I have discovered six, all of which were attached to young plants. In 

 figs. 32e and 32f are shown two of them. The prothallus shown in 

 fig. 32b possessed a lower rounded extremity, which bore rhizoids, and 

 w^hose cells Avere infested with fungus. It was evident, however, that 

 this portion of the prothallus, which may be spoken of as the " primary 

 tubercle," since it corresponds to the region in the prothallus of 

 L. cer?iuum which has been given that name by Treub, is not the first- 

 formed part of the prothallus, for its cells were continued below into 

 an empty-celled j^rocess which had been broken ofi short. The shaft is 

 very much longer than in any of the prothalli of L. cernuum or 

 Jj. laterale. Half-way up the shaft was a filamentous projection which 

 bore sexual organs. On the opposite side of the shaft to this process two 

 epidermal cells were infested by the fungus. At its upper extremity 

 the prothallus was expanded into a bulky mass of tissue. The cells 

 of the underneath region of this massive tissue showed the presence of 

 fungus, and a group of rhizoids sprung from the same region. Imme- 

 diately below the upper surface of the prothallus the necks of archegonia 

 could be seen. Fig. 32c is that of a prothallus in which there were no 

 fewer than five separate fungal regions along one side of the shaft. It 

 was noticeable that each one of these regions was swollen and rounded, 

 as if the presence of the fungus had sei'ved to stimulate the growth of 

 the cell-tissue. A group of rhizoids was borne on each one of these 

 fungal regions. Filamentous outgrowths with archegonia at their base 

 occurred in two places on the main shaft, opposite to the fungal zones. 

 This prothallus was 4 mm. in length. I did not observe wlietlier it 

 was growing upright or horizontal. All of the extended prothalli were 

 dissected out of short moss and slime fungus which was free from soil 

 and decayed humus, and possibly the abnormal length of the shaft is to 

 be put into connection with the depth at which the spores germinated 

 below the surface of the moss, while the presence of several fungal regions 

 bearing rhizoids is due to the absence of humus in the layer in which 

 the prothalli were growing, and to the consequent dependence of the 

 latter upon the intracellulai- fungus for much of the required food. 

 In fig. 32d is shown another prothallus, whose total length was about 

 4-^ mm. It bore two groups of filamentous processes, at different jalaces 

 on the shaft. There were ' several fungal regions, all of which bore 

 rhizoids, and were slightly swollen, though to a less extent than in the 

 prothallus shown in fig. 32c. The four lower gx'oups of fungus-contain- 

 ing cells were situated on the same side of the shaft, and were so close 

 totjether that thev almost formed one continuous zone. It will be noticed 

 that in this particular protliallus the lowest fungal region is scarcely 

 tubei cular in form, and that it is continued below into a tapering 

 empty-celled filament, which was probably the region of the prothallus 

 first formed from the spore. The two uppermost fungal regions are or 

 the side of the shaft opposite to the others. Tlie long shaft is expanded 

 above into a somewhat bulky crown, which liears filamentous and lobe- 

 like foliar expansions. A diminutive young plant which had developed 

 a single protophyll was attached to the crown of this prothallus, the 



