94 



reproduction in D. capensis as arising not from latent embryonic 

 tissue but from ordinary epidermal cells at the apex or near the 

 petiole of the leaf, or upon the petiole itself. 



Goebel (Einleit. i. d. exp. Morph. d. Pflanz. 196./. gy. 1908) 

 describes and figures a portion of a leaf of D. binata, a species 

 whose leaves fork into two long segments. If a part be cut 

 away and placed in a moist chamber it develops adventitious 

 shoots, which have leaves like those of D. rotundifolia instead of 

 being like the parent plant in form. This is the only species so 

 far observed, in which young plants which arise by proliferation 

 from mature tissue, develop leaves different from those of the 

 adult. The question arises as to whether D. rotundifolia is not 

 near to the antecedent form in structure while D. binata may be 

 the result of the greatest modification, so that it is still in a state 

 of variation and hence reverts to the D. rotundifolia type. 



An allied form of reproduction which occurs in D. pygmaea, 

 a native of southern Australia and New Zealand, is described by 

 Goebel (Flora 98 : 324. 1908). The leaves are arranged in a 

 rosette like those of other species but they are peculiar in having 

 a peltate form and little chlorophyll, the work of assimilation 

 being carried on chiefly by the petioles which are fleshy, contain 

 much chlorophyll, and have stomata. At the close of the vege- 

 tative period, in the latter half of October in cultivated plants, 

 numerous brood-bodies which resemble the gemmae of Mar- 

 chantia appear in the center of the rosette. Each is borne upon 

 a slender hyaline stem, the turgid cells at the apex of which set 

 up such a tension that the brood-bodies are easily broken off by 

 the animals which pass over them or by the rain. These small 

 (0.730 mm. by 0.5 1 5 mm.), heart-shaped brood-bodies show dor- 

 so-ventral differentiation, the under side being smooth while the 

 upper side is rounded into a horse-shoe-shaped cushion. There 

 are stomata on both sides and a vascular bundle runs from the 

 point of attachment to the center of the brood-body. The tissues 

 are rich in starch, fat, and other reserve foods. The anlage of 

 the new plant lies in the hollow at the base and may develop 

 immediately after separation from the parent plant if conditions 

 are favorable, drought being the most serious hindrance. The 



