466 



NATURE 



[September 17, 1891 



complete accord with the view which I have several 

 times expressed in regard to the chlorophyll corpuscles of 

 Hydra viridis and of Spongilla viridis (see Quart. Journ. 

 Micr. Set., vol. xxii. p. 229), viz. that there is no more 

 reason for regarding them as symbiotic Algas than there 

 is for so regarding the chlorophyll-corpuscles of a butter- 

 cup. Whether there is sufficient reason for so regarding 

 the chlorophyll-corpuscles of a buttercup is another ques- 

 tion, and one which certainly is not yet decided in the 

 affirmative, though there are considerations which render 

 such a hypothesis one not lightly to be dismissed. 



A difficulty in the matter seems to be this — viz. that if 

 the chloroplasts of the cells of multicellular organisms are 

 to be regarded as parasitic, why should not those of uni- 

 cellular Alg^ also be regarded as parasitic ? and if " Zoo- 

 chlorella," or whatever the hypothetic Alga may be called 

 in the case of Convoluta, can form chloroplasts, why should 

 not the tissue-cells of Convoluta themselves, or of Hydra, 

 or of Spongilla form chloroplasts ? 



It is obviously necessary to distinguish for the present 

 {though, possibly, as Haberlandt suggests, the one may be 

 derived from the other) the strongly-marked unicellular 

 parasites of Radiolaria and Anthozoa (the "yellow cells") 

 from the green cells of Convoluta, and the chloroplasts of 

 Hydra viridis, of Spongilla fluviatilis, and of many 

 Ciliata. The statement which is current as to the exist- 

 ence of a nucleus in the chloroplasts of Hydra is simply 

 erroneous, and that as to the independent multiplication 

 of the chloroplasts of Ciliate Infusoria when removed 

 from the cell in which they occur is possibly a misinter- 

 pretation of a graft-phenomenon. It is to be hoped that 

 Dr. Haberlandt will spare the time to study for himself — 

 as he has the green cells of Convoluta— the more readily 

 obtainable chloroplasts of Hydra, Spongilla, and Stentor. 



Some extremely interesting and suggestive remarks on 

 the physiological and biological phenomena connected 

 with the green cells of Convoluta conclude Dr. Haber- 

 landt's chapter. E. Ray Lankester. 



STREATFEILUS PRACTICAL ORGANIC 

 CHEMISTRY. 



Practical Work in Organic Chemistry. By Fredk. Wm. 

 Streatfeild, F.I.C., &c., Demonstrator of Chemistry at 

 the City and Guilds of London Institute's Technical 

 College, Finsbury. With a Prefatory Notice by Prof 

 R. Meldola, F.R.S. " Finsbury Technical Manuals." 

 (London: E. and F. N. Spon, 1891.) 



'T^HE numerous manuals of practical organic chemistry 

 -L which have been published of late years testify to 

 a re-awakened interest in an important subject. Some 

 of these deal with the preparation of various typical 

 organic compounds ; others restrict themselves to de- 

 scribing methods of analysis. The present work com- 

 bines both methods of teaching, and, as a special feature, 

 divides the subject into "programmes of instruction" 

 designed to meet the varied wants of the students attend- 

 ing the evening classes of chemical technology at the 

 Finsbury College, taking into account the special nature 

 of their daily avocations and the purpose to which they 

 NO. 1 142, VOL. 44] 



wish to apply their chemistry. Thus, after working 

 through the introductory courses of " operations " and 

 ''analysis," and thus familiarizing himself with the 

 general methods of the subject, the student would begin 

 to specialize. The brewer would select the programme 

 "ethyl alcohol and its reactions," which includes fer- 

 mentation and the purification and estimation of alcohol, 

 and touches on allied subjects, such as the preparation of 

 aldehyde, acetic acid, and chloroform. The soap-maker 

 would devote himself to the programme, " a study of the 

 preparation and decomposition of ethyl acetate, and of 

 the composition and reactions of some of the natural 

 fats and oils " ; thus passing from the simplest case of 

 saponification (hydrolysis) of an ethereal salt in ethyl 

 acetate to the more complex cases in the fats. This latter 

 programme also includes the isolation and estimation of 

 glycerol, and its properties ; palmitic, stearic, oleic, and 

 ela'i'dic acids ; drying and non-drying oils ; bromine and 

 iodine absorption of oils ; and other matters of interest in 

 this connection. The tar-distiller would carry out the 

 experiments given under "coal-tar and coal-tar pro- 

 ducts" — a very full and satisfactory chapter. 



This restriction of the field of study is amply justified 

 by the necessities of the case, and only an irreclaim- 

 able scientific purist would object to it. Even the 

 ordinary day-student of chemistry, who can devote his 

 whole time and energies to the subject, must work under 

 some similar limitation when he comes to deal with the 

 inexhaustible material of organic chemistry. 



The experiments given under the various programmes 

 are well selected, and the accompanying descriptions are 

 evidently the outcome of a thorough practical knowledge of 

 the subject. We may make an exception, however, in the 

 case of the preparation of anhydrous formic acid (p. 66) 

 by passing sulphuretted hydrogen over dry copper for- 

 mate. The method is quite obsolete : Lorin's improved 

 process of preparing the pure acid from anhydrous 

 glycerol and anhydrous oxalic acid, drying the 95-98 

 per cent, acid thus obtained with boric anhydride, is now 

 employed. Worst of all, the author recommends in this 

 experiment that the sulphuretted hydrogen should be 

 dried by passing it through concentrated sulphuric acid 

 — a blunder which would go far to justify the prevailing 

 impression that organic chemists are not always suffi- 

 ciently conversant with the facts of inorganic chemistry. 



In spite of this and one or two other trifling in- 

 accuracies, we cordially recommend the book as a 

 valuable aid to both teacher and student. What it 

 deals with really is practical organic chemistry, and not 

 the spurious substitute which, in the shape of " the detec- 

 tion of not more than one organic acid and one organic 

 base," usurps the name in this country — thanks to the 

 authority of examining boards, the industry of the writers 

 of cram-books, and the credulity of the public. 



Prof. Meldola, in his prefatory notice, referring to the 

 evening classes in chemistry at the Finsbury College, says 

 that they " cater for no examination " ; and it is perhaps 

 owing to this important circumstance that Mr. Streatfeild, 

 on whom a considerable share of the laboratory teaching 

 of these classes devolves, has been in a position to write 

 a real manual of practical organic chemistry, and not a 

 mere cram-book of tests— written up to syllabus. 



