PARTHENOGENESIS. ' li;; 



ill. 'in Beem to be undesired guests; they promote no pollination, and fruits are nut 

 ripened. I have sought vainly for fruits in the neighbourhood of Laibacfa in < 'arniola 

 where Stellaria bulbosa is very abundant; there were thousands of faded llowers, 

 but never a fruit with ripened seeds. Its filamentous subterranean stems, on the 

 other hand, bear innumerable white buds; and if one digs up a handful of the 

 black woodland mould, it simply teems with these offshoots. The little streams in 

 spate after a thunderstorm often wash away some of the humus from their banks, 

 exposing and carrying away these little buds in the whirl of waters. Ultimately 

 they are left somewhere, high and dry; and if the conditions are favourable, take 

 root and establish themselves in these new localities. In this manner, at the 

 present time, is Stellana bulbosa propagated and distributed. We cannot suppose 

 things have always been thus; we are driven to the conclusion that in this case, 

 also, the plant, much restricted as to its distribution, is a fragment of a vanished 

 flora. In the Karst district of Camiola and Croatia such fragments are not infre- 

 quent, and when one puts all the facts together one may well conclude that this 

 flora has retreated or been driven back in a south-easterly direction at a period not 

 very remote from our own. Accompanying these changes there may well have 

 been changes in the distribution of the insect-fauna, and those insects which 

 formerly visited the now rare Stellaria bulbosa of the Karst, and were of great 

 importance to it, may have migrated eastwards or indeed have become extinct. 



PARTHENOGENESIS. 



At the commencement of the Nineteenth Century the attention of Botanists was 

 directed to a certain aquatic plant, widely distributed in the Old World from 

 Ireland to China, and from Finland to Northern Africa, and occurring very 

 commonly on the Baltic littoral and its islands. This plant was Chora crinita, one 

 of the Characeae, which flourishes in brackish water near the sea, and here and 

 there in salty, stagnant inland lakes. In whatever ditch or pool it takes up its 

 abode it occurs in large quantities, and forms, like many of its allies, extensive and 

 luxuriant masses. It is an annual plant, dying off in the autumn. Next spring 

 young plants arise from the oogonia which have passed the winter on the muddy 

 bottom — and so from year to year. Chara crinita is dioecious, that is to say, some 

 plants bear oogonia only, others antheridia (cf. p. 62). Whilst in the generality 

 of dioecious Characeas the male and female plants grow in one another's immediate 

 vicinity, in Ohara crinita such a distribution is extremely rare. Hitherto, male 

 plants have only been found at Courthezon, near Avignon, in the South of France; 

 near Gurjew on the Caspian Sea; and at Salzburg, near Hermannstadt, in Sieben- 

 bürgen (Hungary). I have myself found plants bearing antheridia in some little 

 salty pools near Soroksar, south of Buda-Pesth in Hungary. In the North of 

 Germany on the shores of the Baltic, where Chara crinita is very abundant, a 

 male plant has never been found. Nor have Botanists been wanting in their 

 endeavours to find such, should any occur in this region. The Dassower See near 



