FKKSH-W ATE 11 ALG^E OF Till'. IMTKD STATES. 175 



FAMILY HYDKOGASTRK/E. 



rianlulie minim:! 1 , tcrrestres, gregariie. Cellula initio globo.su, postca clavato- vcl pyriformi- 

 iiilumescens, lui.-i atteuuata elongata ct in ramulos subtilligsiiuos hyalinos partita. Cytioplasma 

 MUfilairiiiii.-iiiii, ii-tutc pmvcrta gonidia dtvi.sione siniultanea transforraaturu. Cytiodenua lamellotmm 

 let ate jmiveetii dilubeiis ct coutabescens ct gonidia libcrans. 



Plants very small, terrestrial, gregarious. Cells in the beginning globose, afterwards clavate or 

 jivrifiirm, with an elongated, attenuated base, divided into very fine, hyaline branches. Cytioplasm 

 mucilaginous, at imiturity transformed by a simultaneous division into gonidia. Cytiodcrm lamel- 

 late, at maturity wa.-tinir, withering away and setting free the gonidia. 



kK. The Hydrofjtistrece are curious little unicellular plants, which grow 

 upon wet earth. The matured frond is swollen up at one cud to form a subglobular 

 or pyriform head, whilst at the other end it is produced into a long, much-branched, 

 line root-like portion which enters the earth and maintains the little plant in 

 its upright position. The green endochrome is contained almost entirely in the 

 head, and forms generally a coat or layer in the outer portion of its cavity, the inner 

 part of which appears to be occupied by a water)' fluid. 



The only specimens which I have seen of this family were found growing in the 

 mud left by the receding water of a recently drawn mill pond, by Dr. Billings, U. S. A. 

 When I got them they were thoroughly dried up, and consequently no opportunity of 

 studying their development was afforded. According to Kiitzing and Braun, the 

 speeics is propagated ordinarily by the breaking up of the chlorophylous layer of pro- 

 toplasm lining the wall of the cell into a larger number of very small globular spores. 

 These, although not endued with the power of motion, seem from their method 

 of formation and history to be homologous with zoospores. In most cases they 

 are set free by the membrane of the parent-cell becoming gelatinously softened, 

 swelling up, collapsing, and finally dissolving away. The little protococcoid cells 

 then enlarging, develop at one end a hyaline prolongation which penetrates into 

 the Around. Growth and development continuing the upper end of the cell swells 

 up into the ovate or globular head, whilst the lower becomes the hyaline, branch- 

 in;,'. root-like portion of the new frond. No indication of this method of repro- 

 duction was discoverable in the plants which Dr. Billings sent me. The evident 

 affinities of the family with the Vaucheriaccce render it exceedingly probable that 

 there is in it some method of sexual reproduction, as yet undiscovered, allied to 

 that which occurs in the latter. In some of the specimens sent me, there were 

 what appeared to be resting-spores (pi. XVI., fig. 2 a), occupying the whole of the 

 cavity of the cell, from which they appeared to be finally discharged by a decav 

 and rupture of the outer coat or wall. How these bodies were formed, and whether 

 they really have power to reproduce the species I cannot telL 



Genus HYDEOGASTRUM, DESV. 



Character idem ac familite. 

 Characters that of the family. 



H. ffranulatnm, (LINN.) DESV. 



H. plemmqne gregarium, sicpe npgregntum, hand raro eonflticna ; cellula e globoso-pyriformi, 

 magnitudine scminis papavcris vcl sinapios et ultra, prasino-viridi supcrficic pulverulent*. (R.) 



