122 THE AMERICAN MONTHLY [Apr., 



was found in the results given by the various mixtures but the 

 per cent solution was the most satisfactory. 



The chief advantage of this method is that it dispenses with 

 the need for an alcohol lamp; an important and, in the hands 

 of the inexperienced, a somewhat dangerous adjunct of the lab- 

 oratory is thus removed from constant use. The greatest dis- 

 advantage is that, as in all collodion methods, the collodion is 

 liable to take the stain and refuse to give up the color to treat- 

 ment. Practically, however, in using the ordinary hematoxy- 

 lins, eosin, picric alcohol, etc., there is no difficulty ; it is only 

 with the stronger stains that trouble is found. The use of this 

 thin coat of collodion is a simple and effective method for gen- 

 eral histological purposes. 



Preparing Fresh-water Algse. — M. F. Pfeiffer has pub- 

 lished quite recently in the "Jahrbacher fur wissenschaft. Bo- 

 tanik (Bd XXVI, Heft IV) a recapitulation of the technical 

 preparation of fresh-water Algse. This work is divided in two 

 parts ; the first includes a description of the various reactive 

 instruments, colouring matters, preservative liquids, stones of 

 inclusion, fastening of the preparations. The second part is 

 practical. 



It consists of a great number of lists divided into five columns. 

 In the first one the name of the Alga is to be found, the se- 

 cond gives the means of fixation. A third columra indicates 

 preservative liquids to use. Tbe following column furnishs us 

 the coloring liquids. Then the last contains the inclusions, 

 to employ. 



The author passes thus in review the following Algse : Ba- 

 trachospernum, Hydrurus, Coleochaete, Bulbochaete, Oedogonium, 

 Frasiola, Hormiscia, Chaetophora, Draparnaldia, Stigeoclonium, 

 Conferva, Microspora, Trentepholia, Microthamnion, Cladophora, 

 Vaucheria, Volvox, Pandorina, Scenedesraus, Pediaslrum, Sorastrum., 

 Coelastrum, Ophiocyiiura, Raphidium, Tetraedron, Eremosphaera, 

 Tetraspora, Dictyosphaerium, Nephrocytium, Gloeocystis, Botryococcus 

 Palmella, Pleurococcus, Protococcus, Euglena, Mesocarpns, Mougeo- 

 tia, Zygnema, Spirogyra, DesmvUuim., Hyalotheca, Sphaerozosma, 

 Gymnozyga, Spirotaenia, Closterium, Penium, Tetmemorus, Disphinc- 

 tium, Pleurotaeniopsis, Xanthidium, Cosmarium, Arihrodesmus, 

 Euastrum, Micrasterias, Staurastrum. 



As can be seen from this long list, M. Pfeiffer has gathered in 



