276 THIRD GROUP. VASCULAR CRYPTOGAMS. 



prothallium of Lycopodium evidently bears several archegonia, for Fankhauser found 

 on it other plants in less advanced stages of development as well as the one which 

 was more fully grown. From the point of attachment of the plants to the pro- 

 thallium it may be gathered that the archegonia are formed on the upper surface 

 at the bottom of the depressions between the lobes. 



The second or asexual generation (sporophore^ sporophyte). It follows from 

 what has been said above that nothing is known as to the formation of the embryo. 

 The young plants found by Fankhauser were however sunk in the tissue of the 

 prothallium by means of a swollen knob about the size of a pin's head, which 

 evidently answers to the foot of the Ferns and is a lateral formation at the base of the 

 stem and of the first root. 



The habit of the full-grown plant is remarkably different in the different genera. 

 There are species of Lycopodium with erect stem and branches, as L. Selago ; in such 

 cases the roots which arise in the lower region of the stem often grow downwards 

 in its tissues and only issue in a tuft at its base as in L. Phlegmaria, L. alvifoltum, and 

 others. In many species on the other hand the primary stems and the strongest 

 branches creep on the ground, sending roots into the ground at various points, and 

 only certain leafy shoots, the forked branches especially which bear the sporangiferous 

 spikes, grow upwards ; such forms as these show a tendency to dorsiventrality, 

 especially in the structure of the axile vascular bundle. All the species are thickly 

 clothed with small, often narrow elongated leaves. The variety of habit depends 

 chiefly on the more or less vigorous development of the individual branches of the 

 bifurcating shoots. The sporangia are found at the base of ordinary foliage leaves in 

 L. Selago, but more commonly on leaves of a different shape and colour which form 

 the terminal spikes of special fertile shoots often of peculiar formation. 



Phylloglossum, a small Australian plant a few centimetres high which sends 

 up its stem from a small tuber, is very unlike Lycopodium ; the stem produces a 

 rosette of a few long leaves and one or more lateral roots at its base, continues 

 upwards as a slender scape, and ends in a spike of sporangia with small leaves. The 

 plant is reproduced by adventitious shoots consisting of a tuber with a leafless 

 rudimentary bud, and in this respect resembles our own Ophrydeae *. 



1 [Bower (On the Development and Morphology of Phylloglossum Drummondii, Part I, Vege- 

 tative Organs in Proc. Roy. Soc. vol. xxxviii. p. 445, a summary of the paper whidh will 

 shortly appear in the Philosophical Transactions), has recently investigated the morphology of 

 this interesting genus. Tubers sent from Australia were successfully grown at Kew, and Bower gives 

 a summary of the results of his examination of them in the following words : ' The mode of 

 development depends to a certain extent upon the size of the tuber : where the tubei 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 developes 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 



