ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 61 



a free medusa. In all cases the mother-cells do not appear in 

 any part of the gonophore, but in the coenosarc. Taking the first- 

 named species, he found that before the appearance of any gono- 

 phore large highly-refractive cells appear in the endoderm of the 

 coenosarc ; the jiresence of a certain number of these mother-cells 

 determines the formation of a gonophore. Very soon the primary 

 mother-cells multiply with great rapidity, and the daughter-cells, 

 which are much smaller, form a horseshoe-shaped testicular mass, 

 which, growing rapidly, ceases to form part of the endodermic wall, 

 owing to the reconstitution of the unaltered endodermal cells, which 

 now form a continuous layer below it. This explains the origin of 

 the statement that the testicular cells are ectodermic in origin. 

 There is, further, a great similarity between the development of the 

 male and female elements. The author thinks that there is no true 

 alternation of generations. 



Porifera. 



Attempt to Apply Shorthand to Sponges.* — The system here 

 elaborated by Dr. G. C. J. Vosmaer is an extension of that first intro- 

 duced by him in a paper on the Desmacidince of the Leyden Museum,! 

 and its object is to give shortly the characters of a sponge by symbols 

 which denote its several spicules. In the present scheme he tries to 

 make his system of symbols so elastic as to admit almost any possible 

 combination of characters in a spicule. Of course it is only applicable 

 to sponges which have spicules, and does not take account of the 

 Carnosa or the Horny Sponges ; neither does it take account of the 

 proportions (though the worker may readily add these himself) ; the 

 author admits that it is not applicable to all cases, but claims for 

 it the recommendation of saving some time and trouble in description. 

 It is impossible to give here all the full formulae used, so that in most 

 cases only the abbreviations are given, which can be combined 

 according to the requirements of different cases, and may help 

 students of sponges to arrange for their own use, at any rate, methods 

 of expressing shortly the often complicated spicular complements 

 which may be met with. Dr. Vosmaer has used it for three years. 



For monaxial (i. e. linear) spicules are used :—tr (truncate) = 

 blunt-ended ; tr tr = blunt at both ends, but not to same extent ; tr ac 

 (acute) = blunt at one end, pointed at the other (acuate, Bowerbank) ; 

 ac ac = doubly-pointed, to different extents. Where the forms of the 

 ends are similar, the formula is tr"^, ac"^, &c. ; tr^ tr = clavate or 

 spinulate cylindrical, and /r° ac stands for the common spinulate or 

 " pin-like " form ; / = fusiform, sp = spined. Combinations of these 

 signs supply formulae for the thirty-two modifications of straight mon- 

 axial spicules. For curved forms of the same group the following 

 abbreviations are used. An inverted V (/\) for the tricurvate acerate, 

 an S on its side (CO) for the bihamate ; the same with two lines 

 drawn across it, so as to make it resemble the sign for a dollar, stands 

 for trenchant contort bihamate ; anc is anchorate, anc^ is tridentate 



* Tijdsch. Niederl. Dierk. Vereen., v. (1881) pp. 197-206 (1 pi.), 

 t See this Journal, iii. (1880) p. 661. 



