66 NOTICES OF BOOKS AND MEMOIRS. 



plants under examination, and to ascertain whether there was any 

 pollen produced by any of the flowers. In no instance was a trace 

 either of anther or of i)ollen-grain found. OoidIous details are 

 given of the thh-ty flower-buds examined, and from which seventeen 

 fruits were obtained. Considerable difference was observed in the 

 period of swelling of the ovary, which commenced sometimes four 

 days after maturation of the stigma, but sometimes not until after 

 twenty-five, thhty-eight, or thhty-nine days ; the time elapsing 

 between commencement of swelling and perfect maturity also 

 oscillated between fourteen and thirty- eight days. Nineteen embryos 

 were found in the seventeen fruits : of these five were solitary in 

 one cell of five fi'uits, a sixth and a twin-pair occurred in two cells 

 of a sixth fruit, a triplet in one cell of a seventh, and quadi'uplets 

 in one cell of an eighth and ninth fruit. All these embryos are 

 figured : they vary considerably in tlieii- size and shape, and in the 

 degree to which then- perfection is carried. The author enters 

 somewhat minutely into the philosophy of parthenogenesis, and 

 gives a full list of plants in which this method of reproduction has 

 hitherto been found, omitting Cannabis and MercuriaUs however. 

 The investigation was conducted conjointly with Alexander Braun, 

 who thus returned, quite at the close of his career, to a subject in 

 which he had formerly taken such deex^ interest. 



S. M. 



Acetahularia mediterranea. Yon A. de Bary und E. Strasburger. 

 (' Botanische Zeitung,' Nov. 1877.) 



It was only the other day that we di-ew attention to the 

 discovery of another case of conjugation of zoospores, viz., in 

 Botrydium fjranulatum. We have now to mention a similar dis- 

 covery in the case of the ciuious alga mentioned at the head of 

 this notice. The authors set themselves the task of finding out 

 w at becomes of the spore, the subsequent history of which has 

 hitherto remained unknown. The ripe spore is about ninetj'-five 

 micro-millimetres long by about seventy broad, and it is provided 

 with a lid. On the inner side of the wall is a thick layer of 

 protoplasm, containing a great number of starch-grains coloured 

 green by chlorophyll. The central space is filled with water-like 

 fluid, in which lies an accumulation of small red pigment -grains 

 collected always close to the inner side of the layer of protoplasm. 

 The starch afterwards dissolves, and the now homogeneous plasma 

 divides simultaneously into numerous nearly equal j)olyhedral 

 portions arranged in a single row except perhaj)s near the lid, 

 which latter after a while bulges outwards, and in this movement 

 is closely accompanied by the contents. Suddenly the lid is 

 uplifted, and the contents immediately project, surrounded by a 

 swollen enveloping membrane. The lid usually remains, as it 

 were, hinged to the spore, and seldom is quite cast off. The por- 

 tion of the contents which has escaped from the spore usually 



