Aug. 17, 1876] 



NATURE 



327 



vertices was one of the stages. Details of the experiments 

 are given, and Schroeter concludes that AUcidium nrticcB 

 is a stage of Puccinia caricis. In a note to his paper, Dr. 

 Schroeter mentions that Dr. Magnus, of Berlin, has made 

 similar experiments with the same result, an important 

 confirmation of the remarkable habit these curious plants 

 have of changing from one host to another, and at the same 

 time changing the form of their spores, a condition described 

 by De Bary long ago in the rust of wheat. A second 

 form noticed by our author is a species of rust common 

 on many grasses. It has many names, and Dr. Schroeter 

 calls it Uromyces dactylidis, Ottli, {Uromyces graminis, 

 Cooke). One stage is spent in our common grasses, 

 such as Dactylis glofnerata, Poa iiemoralis, P. trivialis^ P. 

 annua, P. praiensis, &c. The other stage occurs on 

 Ranunculus bulbosus, R. repens, and 7?. polyanthemos, and 

 is known as j^Ecidiuni Ranunaclacearum, D.C. The yEcidia 

 occurring in other Ranunculaceae {Clematis, Thalicirmn, 

 &c.) seem to belong to other species. Dr.L. Just's paper is 

 a physiological one, showing the efifect of the epidermis 

 of the apple in preventing loss of water by transpiration. 

 The third paper, by Dr. J. Schroeter, on the efifect of 

 disinfectants in lower organisms, shows markedly the 

 value of carbolic acid in destroying germs. In the fourth 

 paper Dr. A. B. Frank shows how light influences the 

 relative time of development of the flowers in a catkin, 

 those flowers opening first which receive the most light. 

 Next follow two papers by Dr. Ferdinand Cohn, one on 

 the " Function of the Bladders of Aldrovanda and 

 Utricularia," the other on the " Development of the genus 

 Volvox." English readers are already acquainted with 

 the more important facts recorded in the first paper, as 

 they have already been made use of by Mr. Darwin in 

 his work on *•' Insectivorous Plants." The second paper 

 is of especial interest in relation to the re-distribution of 

 the Thallophytes, by Prof. Sachs, in the fourth edition of 

 his justly celebrated " Lehrbuch." The structure of volvox 

 is carefully described, and its modes of reproduction both 

 sexual and non-sexual. The non-sexual reproductive 

 cells Cohn calls Parthenogonidia. Non-sexual reproduc- 

 tion seems to take place during the whole year, and the 

 alternation of generations is completed by the occurrence 

 of sexual reproduction in the spring. The volvox-colony, 

 or caenobium, is either monoecious or dioecious, the female 

 cells, or Gynogenidia are either produced along with the 

 male cells, or Androgonidia, in the same colony, or they 

 are not. Cohn proposes to divide the Linnaean Volvox 

 globator into two sub-species, namely, {a) Volvox vionoicus, 

 and ib) Volvox dtoicus, the former having both andro- 

 and gynogonidia, the latter either one or other. The 

 structure of Volvox is very like that of Pandorina, 

 but the reproduction is like that of Sphaeroplea, and it 

 belongs, not to the Zygosporeae, which have conjugating 

 zoospores, but to the Oospores. Cohn, however, does 

 not consider the Zygospores and Oosporeae to be separate 

 classes of the Thallophyta, but only to be subdivisions of 

 one class, to which he gives the name of Gamosporeaj. 

 The next division Cohn calls the Gamocarpeas, a division 

 quite equivalent to Sachs' Carposporese. In the Gamo- 

 carpese there are two methods of fertilisation. One by means 

 of the Pollinodium, analogous to the conjugation in the 

 Gamosporene, the other by Spermatia, resembling the 

 Spermatozoids. In the higher plants a somewhat similar 



arrangement exists ; the MuscinCcC and Vascular Crypto- 

 gams having Spermatozoids, while the flowering plants 

 have pollen and pollen-tubes, showing a certain analogy 

 to the pollinodium of some of the Carposporeae. 



Dr. Richard Sadebeck contributes a paper on the re ■ 

 markable parasite living in the cells of the prothallium of 

 Equisetum, and called Pythium equiseti. It belongs to 

 the Oosporeae, and its structure and life-history is here 

 well described. 



The part concludes with two papers, " Researches on 

 Bacteria," Parts II. and III. The first is by Dr. Cohn, 

 and is a continuation of his paper with the same title in 

 the second part of the " Beitrage," while the other is by 

 Dr. Eduard Eidam. In the latter paper Dr. Eidam gives 

 details of a series of very interesting researches on the 

 action of different degrees of temperature and of drying 

 on Bacterian Termo. The Bacteria were cultivated in 

 Prof. Cohn's normal nutrient fluid, and the solution kept 

 at definite temperatures for definite periods of time. The 

 activity of Bacteria does not begin until the temperature 

 rises above -4- 5° C. -|- 5^°, being the temperature at 

 which they begin to multiply, although very slowly. 

 Between 30° and 35° C. the multiplication is most rapid, 

 but at 40° the activity again diminishes, and the Bacteria 

 in the nutrient fluid are killed by exposure for fourteen 

 hours to a temperature of 45° C, or for three hours at a 

 temperature of 50° C. "When dried the Bacteria can 

 retain their vitality for a long time at high as well as at 

 low temperatures. All these experiments are of especial 

 interest at the present time and seem to have been con- 

 ducted with great care. Prof. Cohn's paper deals chiefly 

 with descriptions of new or imperfectly known genera and 

 species, and concludes with an attempt at grouping the 

 different genera of Bacteriaceae according to their natural 

 affinities. The close relation of Bacteria to the Phyco- 

 chromaceas is pointed out, and it is shown to be impos- 

 sible to erect the Bacteriaceae into a family separate from 

 the Phycochromace?e. Naegelis' name of Schizomycetes 

 is objected to on the ground that Bacteria are not fungi, 

 and the term Schizophyta proposed for the group instead. 

 This group is nearly equivalent to and would take the 

 place of Sachs' first class of Thallophyta, namely, the 

 Protophyta. The Schizophyta includes two tribes : (i) 

 Gloeogena?, in which the cells are either free or united by 

 gelatinous substance ; and (2) Nematogenae, which are 

 filamentous. To the first tribe belong such genera as 

 Chroococcus, Micrococcus, Bacterium, Aphanocapsa, 

 Gloeocapsa, Clathrocystis, Sarcina, Polycystis, &c. ; while 

 to tribe 2 belong Beggiatoa, Oscillaria, Vibrio, Spirulina, 

 Anabasna, Nostoc, Rivularia, Cladothrix, Scytonema, &c. 

 The paper is an exceedingly interesting one, and has 

 most important bearings on the classification of the 

 Thallophytes. W. R. McNab 



FERNETS PHYSICS 



Cours de Physique. Par E. Fernet. (Paris : G. Masson, 



Editeur, 1876.) 



FROM the great success which attended the publica- 

 tion of Prof. Ganot's " Elements de Physique," due 

 in a great measure to the excellence of its illustrations, and 

 followed as it was a few years later by the splendidly got 

 up "Traitd" of M. Deschanel, which has been so ably 



