NoVEMiiKlt It, ItS^S.] 



SCIENCE. 



ti31 



nomycetes not treated in the fust volume, together 

 with an index of all the genera and species of the 

 order. Tliere are also several pages of addenda to 

 both volumes, including the species published up to a 

 very recent date. In fulness and general arrange- 

 ment, the present volume has the same merits as ils 

 predecessor. Vol. iii. is announced to appear in 1S84, 

 and will include the Sphacropsoideae, Jlelanconieae, 

 and Hyphomycetes. — w. c. r. [345 



Illustrations of British fungi. — This compre- 

 hensive and finely executed work by M. C. Cooke has 

 now reached the end of the second volume, including 

 eighteen parts and an index. The two volumes al- 

 ready issued include figures of all the leueosporic 

 species of Agaricus known to occur in Britain, except 

 twenty-six little-known species, three liundred and 

 seventy-eight species with varieties being represtntcd 

 — a considerably larger number than is included in 

 the works of Sowerby, Bulliard, or Krombholz. The 

 work will be continued, and contain plates of the re- 

 maining sections of Agaricus. — w. O. F. [346 



Ascospores in the genus Saccharcmyces. — 

 In the re[)orts of the Carlsberg laboratory, Hansen 

 gives a rt'jwnie of his researches on the formation of 

 ascospores in the different foims of Saccharomyces. 

 While in general he agrees with Rees's views, he 

 denies the possibility of distinguishing species of Sac- 

 charomyces by the ascospores; and, in fact, he is 

 hardly inclined to admit the specific value of the 

 different foims described by Rees. Hansen's ex- 

 periments were made with cultures of single spores 

 obtained by a process of dilution, which be describes 

 in detail; and the purity of Jhe cultures was recog- 

 nized by the formation, on the walls of the culture- 

 flasks, of a single spot formed from the growth of one 

 spore. He also adopted, with good results, Koch's 

 method of gelatine culture. While the ascospores of 

 the different so-called specie.'^ of Saccharcmyces can- 

 not he distinguished by their shape, Hansen found 

 that there was a difference in the time of their ger- 

 mination when exposed to different temperatures; 

 and he gives a series of curves to represent the results 

 oi his experiments with regard to the temperature in 

 six different forms. The curves all have a similar 

 form; but the maxima and minima vary with the 

 different species, the minimum being between -J" C. 

 and 3° C, and the maximum about 'd~\° C. There 

 follows a discussion of what Pasteur calls Torulae, 

 which resemblei species of Saccharcmyces, but are 

 separated frcm that genus by Hansen, because he 

 found that they did not produce asccspores. The 

 paper concludes with an account of diseases of beer 

 caused by certain alcoholic feiments. — w. G. F. [347 



ZOOLOGY. 



Worms. 

 Homology of the nemeitean proboscis and 

 the chorda ^dcrsalis. — In an article en the an- 

 cestral form of tlic clicirdala. Ilubrecht dofi iids the 

 following speculative Ihe.-is: "According to my oi)in- 

 ion, the proboscis of the nemerteans, which arii-es 

 as an invaginable structure (entirely deiived, both 

 phylii- and onto-genelically, frcm the epiblasl), and 



which passes through a part of the cerebral ganglion, 

 is homologous with the rudimentary organ, which is 

 found in the whole scries of vertebrates without ex- 

 ception, — the hypophysis cerebri. The proboscidean 

 sheath is comparable in situation (and development ?) 

 with the chorda dorsalis of vertebrates." AVithout 

 adding new facts, but merely basing his arguments 

 on what is already known, the author defends his 

 hypotliesis with great ingenuity. His chief argu- 

 ment is, that the proboscis and the hypophysis are 

 both anterior ectodermal invaginations, and are ho- 

 mologous. His use of terms is misleading. By 'pro- 

 boscis' he designates apparently both the free portion 

 of the proboscis and its sheath; by 'proboscidean 

 sheath,' on the contrary, the posterior portion of the 

 proboscis, which lias no sheath, and is not free. 

 At least, his descriptions became intelligible to the 

 reporter only on that assumption. The posterior 

 unfree part of the proboscis he considers the homo- 

 logue of the notoehord. The vertebrates are not 

 connected with the annelids; but, on the contrary, 

 the two lateral nerves of lower worms have united 

 dorsally to make the central nervous system of ver- 

 tebrates, ■centrally to form the ganglionic chain of 

 annelids and their derivatives. In the second Iialf 

 of his paper, the author endeavors to strengthen 

 his posit l<in by comparisons between other organs 

 in nemerteans and vertebrates. [It is possible that 

 Hubrecht's hypothesis will be verified; but the ob- 

 jections to it come to mind so immediately, and in 

 such throngs, that it is difficult to believe the hypoth- 

 esis well founded. Some of the most serious objec- 

 tions are ably presented by Whitman in an article 

 accidentally published in the same number (p. 376), 

 and arguing in favor of the annelidan affinities of 

 vertebrates.] — (Quart, journ. 7nicr. sc, xxiii. 3-)9.) 

 c. s. M. [348 



Embryology of Planaria polychroa. — Melsch- 

 nikoff has' studied the development of fresh-water 

 planarians. and reached conclusions that are, in part, 

 very startling. PI. polychroa lays its egg-capsules 

 in late spring and early summer. Each capsule con- 

 tains from four to six eggs, and thousands of the so- 

 called ' yolk-cells.' The egg has no membrane. ThB 

 yolk-cclls immediately around each ovum break down, 

 their membranes disappear: but their nuclei remain 

 for a long time distinguishable, although they finally 

 disappear in the embryo, into the composition of 

 which these disintegrated cells enter. The ovum seg- 

 ments, but the cleavage-cells do not cohere, there be- 

 ing no vitelline membrane: on the contrary, each 

 embeds itself in the mass derived from the yolk-cells. 

 In some manner, which is left in complete obscurity 

 by the author's descriptions, the cells from the ovum 

 gradually spread themselves, and form first the 

 pharynx, and then an epidermal layer of thin cells, 

 which encloses the whole of the disintegrated yolk- 

 mass, together with cells from the ovum, embedded 

 in it. In the centie of this mixed parencbym ap- 

 pears a cavity which communicates with the lumen 

 of the pliarynx. This last seizes and swalbjws the 

 surrounding yolk-cells, each intact. The cells scat- 

 tered througli the body form the mesoderm (n.es- 



