SCIENCE-GOSSIP. 



H7 



sides. Sometimes two male cells share the apex, 

 and sometimes it occurs that a male cell becomes 

 applied, not to the trichogyne, but to a male cell 

 which is already seated there. In all cases of 

 more than one male cell becoming attached to 

 a trichogyne, it is said that only one forms an 

 open channel with the trichogyne, the others 

 having no function. It might be inferred that, as 

 an opening exists between the spermatium and the 

 trichogyne, the protoplasm, or the nucleus of the 

 former organ, passes over into the latter to effect 

 fertilization. However, recent observations seem 

 to indicate that it is a matter of indifference 

 whether the nucleus or any portion of protoplasm 

 enters the trichogyne. 



Indeed, the process of fertilization is so peculiar 

 in Batrachospcrmum, that it is a matter of opinion 

 whether it is a true sexual action or not. In the 

 first place, no oosphere or female cell is formed 

 from the protoplasm of the carpogone ; secondly, 

 if the nucleus of the spermatium enters the 

 trichogyne it is said to remain in the upper part, 

 and does not unite with the nucleus of the 

 trichogyne or the nucleus of the carpogone. It 

 even occurs occasionally that protoplasm and 

 nucleus of the trichogyne will pass over into the 

 male cell. Following closely upon the appearance 

 of the opening between the male cell and the 

 trichogyne, a deposition of cellulose takes place 

 inside the procarp, gradually separating the tricho- 

 gyne from the carpogone. This separation may be 

 perfect, or it may be of such a character that a 

 narrow cavity exists, in which, however, no pro- 

 toplasm remains. Short protuberances are now 

 given out from the carpogone, and, growing in 

 length, become divided into short cells. The fila- 

 ments branch, and the carpogone becomes hidden 

 by these, which radiate on all sides. This growing 

 body is the developing fruit or cystocarp, and the 

 only part of the procarp which remains visible is 

 the trichogyne, with attached spermatia. The 

 trichogyne does not wither away, but remains per- 

 sistent. Some of the filaments growing from the car- 

 pagone constitute an investment, or loose covering, 

 to the cystocarp ; others are fertile, and terminate 

 in rounded cells, carposporangia, that each contain 

 a single propagative body, known as a carpospore. 



A carpospore does not develop into a BatracJio- 

 spermum plant, but into a plant totally different. 

 A carpospore gives origin to a kind of crustaceous 

 pellicle covering the surfaces of stones, etc. It is 

 composed of irregular filaments, sometimes united 

 into globular masses. In the perennial species of 

 Batvachospcymum it is this structure which enables 

 the plants to persist. It is capable of growth and 

 reproduction, increasing at the circumference, and 

 reproducing itself by spores. From this peculiar 

 structure arise broad tufts of filaments, each con- 

 sisting of a row of cells, and producing spores similar 



to those of the plant on which the tufts arise. 

 Since this form can reproduce itself through a 

 number of generations, it has long been regarded 

 as a distinct genus, under the name of Chantiansia. 

 The freshwater species of Chantransia live on the 

 most shaded sides of wells, etc., developing chiefly 

 in darkness, whilst the Batyachospetmnm form seeks 

 the light. Portions of the Chantransia form, under- 

 going differences in cell division, grow into the 

 perfect Batrachosperinum plant, which, producing 

 roots, becomes independent. 



This account of Batracliospermiim, incomplete as 

 it is, would be more so if no mention was made of 

 the following. The American botanist, to whom 

 we owe the latest information on the subject of the 

 fertilization of this alga, set himself to answer the 

 following. Seeing there is no union of the proto- 

 plasm of the male cell with that of the female 

 organ, was it necessary for the production of fruit 

 that a male cell should unite with the trichogyne ? 

 And he found this was necessary, for, when he 

 grew, under their natural conditions, female plants 

 isolated from male plants, so that the male cells 

 could not come into contact with the trichogynes, the 

 procarps or female organs did not develop into fruit. 

 189, Beres/ord Street, Cainbcrwell, S.E. 



THE NEW BRITISH MOLLUSC. 

 By J. E. Cooper. 



'PETRICOLA pholadifnrmis, Lawk, is a native of 

 North America, it ranges from Prince 

 Edward's Isle to St. Thomas. In this country it 

 appears to have been first noticed by Mr. Walter 

 Crouch, F.Z.S., at Burnham-on-Crouch, about four 

 years ago. The first specimen found was a dead 

 shell, but Mr. Crouch has since obtained living 

 examples at the same place. In the spring of this 

 year Mr. A. S. Kennard found this species alive 



Petricola plwladifonnis. Lawk. 



near Heme Bay, and the writer picked up several 

 dead specimens on the shore near Sandwich. It 

 thus appears to be established in both the River 

 Crouch and the Thames estuary. How it got there 

 in the first instance is not certain, though probably 

 it was introduced with American oysters. This 

 Petricola bears a very striking external resemblance 

 to the common Pliolas Candida, and may have been 

 passed over by collectors mistaking it for that species. 

 93, Soutliu'ood Lane, //j;;/<i'<ii'i, -V. 



G 3 



