Chapter X —131— Drosera 



and appeared to be a dihydroxymethylnaphthaquinone." This was 

 confirmed by Macbeth, Price and Winzor, who called these sub- 

 stances hydroxydroserone and droserone respectively, determining the 

 constitution of the hydroxydroserone. 



Reproduction by means of gemmae. — The case of D. pygmaea de- 

 scribed by GoEBEL (1908) is one of a small group of species in which a 

 very highly specialized method of non-sexual reproduction takes place, 

 viz., by means of gemmae. D. pygmaea is a very small plant, about 

 1.5 cm. in diameter, and consists of a tight rosette of minute acentri- 

 cally peltate leaves with fleshy petioles which appear to be the im- 

 portant chlorophyllous parts. On the approach of the resting season 

 there are formed small brood bodies, resembling superficially those of 

 Marchantia, clustered in the center of the rosette. The gemma itself 

 is a small, ovate, hard mass of tissue, flattish on the dorsal surface, with 

 a deep depression at the base of the ventral surface, in which develops 

 a minute bud which gives rise to a plant {16 — 14-^17). At the base it 

 is attached to a cylindrical hyaline stalk of some length. At the point 

 of attachment to the brood body it is constricted, and is here fragile, 

 so that the brood body is easily detached. The stalk is marcescent, 

 drying up iw situ. The brood bodies measure about 0.5 by 0.7 mm. 

 and contain an abundance of food in the form of fat and starch. 



I received material of D. pygmaea collected by Dr. Pat Brough 

 near Sydney, N. S. W., in response to my request, on two occasions, 

 viz., in Nov., 1939 and in April, 1940. In the former no signs of gem- 

 mae were to be found; in the latter they were present in various stages 

 of development. In none of the specimens could brood bodies be seen 

 openly exposed, as represented in Goebel's drawing (1908). The plants 

 were perhaps still too young. The structure of the gemmae was as Goebel 

 described them. He suggested their homology with leaves, but it is to 

 be noticed that there is no suggestion of stipules. They arise in a 

 ring about a dished growing point, and stand in several ranks around 

 it {16 — 17). Around them young leaves have already begun develop- 

 ment, the older of these expanding. The gemmae seem therefore to 

 represent the culmination of a growth period, and they would be 

 set free during the winter season in the natural habitat. Professor 

 Buller suggests to me that the rosette, with its gemmae at the center, 

 may be regarded as a "splash cup", Hke those of the bird's nest fungi. 



Of much more general occurrence is another method, namely, by 

 budding from the leaf. This is by no means of recent observation. 

 First seen by Naudin in 1840, it has been described by numerous 

 others, at least thirteen in number. The historical aspect of this mat- 

 ter has been well summarized by Behre (1929). 



Naudin in D. intermedia (1840) and Kirschleger (1855) in D. 

 longifolia had observed the fact of budding from the leaf surfaces, and 

 that the origin was "probably endogenous" (Naudin). Nitschke's 

 account was sufficiently extended and exact so that Behre found little 

 to correct, so far as general morphology was involved. The earliest 

 anatomical study was made by Beijerinck (1886), estabUshing the exo- 

 genous origin of the leaf buds. Leavitt (1899, 1903, 1909) pointed 

 out that the earlier leaves of the leaf buds of even such extreme forms 

 as D. binata, have rounded leaves characteristic of D. rotundifolia, 



