NOTES AND MEMORANDA. , 185 



in passing through a similar development-cycle, show here- 

 after similar sexual conditions, notwithstanding Cramer's 

 and Dodel-Port's record of an act of fertilisation in that 

 genus by means of the fusion of two microgonidia. Ac- 

 cording to Cienkowski this phenomenon would then have 

 to be otherwise interpreted, especially taking into considera- 

 tion the circumstance that the microgonidia of that alga are 

 capable of germination without any such " conjugation " 

 having first taken place. 



The foregoing memoir is preceded by two others on a " pal- 

 melloid" modification of Stigeoclonium and of Ulothrix, in 

 continuation of a previous one by the same author,^ on a 

 *' palmelloid" breaking-up of Stigeoclonium, then increasing, 

 for some time by cell division, their contents breaking up 

 into " microgonidia," which reproduce the filamentous form 

 of the mother-alga ; this, in addition to the longer known 

 (now denominated by the author) " macrogonidia." This 

 *' palmella zoospore-producing state" he records to have found, 

 too, in Hydrocytium, Coleochsete, and others. Hormospora 

 mutahilis and Schizomeris are claimed by the author as but 

 conditions in the palmelloid modifications of TJlothrix mucosa. 

 The memoirs are too long even to abstract here. Researches 

 and results such as these would seem to raise the question 

 how far certain protococcoid and palmelloid " forms," looking 

 distinct and regarded as independent, may be but stages in 

 the development-cycle of algae whose mature and typical 

 forms are " filamentous," and which, although Cienkowski 

 has not, except in Cylindrocapsa, seemingly detected it as 

 yet, may thus probably be found to possess a sexually differ- 

 entiatecl fructification. 



Separation of the Sexes in Sponges. — F. E. Schulze, in the 

 * Zeitschrift fiir Wiss. Zoologie,' gives the result of his study 

 of two species of Halisarca, H. lohularis and H. Dujardini, 

 carried on at Trieste. Halisarca is a sponge genus without 

 spicules of any kind. It has been made the subject of inves- 

 tigation by several observers, and lately by Carter and Barrois. 



Schulze distinguishes as components of the sponge an 

 ectoderm, mesoderm, and entoderm. The ectoderm is com- 

 posed of ciliated cells, which differ markedly from the ciliated 

 cells of the ciliated chambers in that they have no collar at 

 the base of the cilium. The mesoderm consists of gelatinous 

 homogeneous tissue, in which are scattered nucleated rami- 

 fied cells in which Schulze has observed all the ordinary 



^ Cienkowski : " Ueber Palmella-zustand bei Stygeoclonium," in ' Botan. 

 Zeitung,' No. 5, Feb., 1876. 



