446 Morphology of Phylloglossum Drummondii. [June 18, 



for luxuriant vegetative development, seemed to promise a good deal 

 of interest. Baron Ferdinand von Mueller, K.C.M.G., F.R.S., Govern- 

 ment Botanist, Melbourne, with the unfailing energy which prompts 

 him to assist every kind of botanical work, after one or two attempts 

 succeeded in transmitting to the Royal Gardens, Kew, a parcel of 

 tubers in a living condition. These were successfully grown for the 

 first time in Europe. Their examination in the Jodrell Laboratory 

 has yielded the results now communicated to the Society. 



The mode of development depends to a certain extent upon the size * 

 of the tuber: where the tuber is small only vegetative organs are 

 formed, where it is relatively large, the plant may form sporangia. 

 Taking first the simpler case, it is found that outgrowths appear on 

 the broad apex of the tuber, which is before germination a simple, 

 smooth and rounded cone ; these outgrowths are leaves ; their number 

 may vary from one to six or seven. They are arranged in an- 

 irregular whorl, of which the members on one side take precedence of 

 the rest in time of appearance; they constitute in fact a " successive 

 whorl." From the first they are rounded at the apex, and have no 

 single apical cell. The apex of the axis, which has a central position 

 at first, becomes gradually depressed, and is overarched by the 

 surrounding tissue ; it develops directly into the apex of the new 

 tuber, which is accordingly of exogenous origin, and represents in this 

 simpler case the actual apex of the parent plant. By a peculiar 

 localisation of growth this apex becomes inverted, and by a process of 

 development very similar to that of the axillary shoot in certain 

 orchids {e.g., Herminium monorchis), it projects laterally from the 

 parent plant. Meanwhile an outgrowth appears on the opposite side 

 of the axis from that on which the tuber projects, and below the 

 insertion of the oldest leaf : this is the first root. It has been clearly 

 proved, by both external observation and by study of sections, that the 

 root in Phylloglossum is of exogenous origin. Among other known 

 examples of this anomalous mode of root-development it is interesting 

 to note the root of the embryo of Isoetes. In those cases where the 

 tuber is relatively large, sporangia are formed : these are, as is 

 already known, borne upon an elongated axis, which is the direct 

 product of the apex of the tuber. A different origin is necessary in 

 this case for the tuber, and it has been found that the tuber originates 

 in such plants in an adventitious manner, as a depression at the base 

 of the sporangium-bearing axis or peduncle : the details of its 

 development are otherwise similar in this case to that above 

 described. 



A comparison of both external form, and as far as possible of 

 internal structure, between Phylloglossum and the young plants of 

 Lycopodium cernuum described recently by Treub, shows many points 

 of striking similarity : this is so marked that the author draws the 



