290 



made. Dr. Woodward, in America, has not yet tried this 

 glass on Nobert's Knes, and we should be much interested to 

 know what it can do on that test. It is an admirable glass 

 to work with, very nearly as easy as the No. 10, admitting of 

 a glass cover of No. 2 thickness, and not requiring a con- 

 denser. We had recently an ojjportunity of Avorking with 

 this glass at living muscular tissue in the laboratory of Pro- 

 fessor Strieker, of Vienna, and hope soon to try one against 

 the English glasses. The No. 15 costs sixteen pounds. 



Development of Gregarinae. — In a private letter our distin- 

 guished contributor. Dr. Edouard Van Beneden, informs us 

 that he has recently made some highly important observa- 

 tions on the development of the Gregarinae of the Lobster, 

 which he described in detail in the January number of our 

 Journal for this year. He has observed the formation of the 

 pseudo-navicells, and finds that these give rise each to a 

 protoplasmic body with two long processes, one of which is 

 very mobile like the apj^endage of Noctiluca ; the other is 

 motionless, but elongates, growing at a great rate, and at 

 length separates from the rest of the mass, becoming the adult 

 Gregarine ; thus in its separation from the original form by 

 division recalling the metagenesis of Echinoderms. Dr. Van 

 Beneden has also carefully traced the formation of the an- 

 terior chamber of this species. The importance of these ob- 

 servations, as far as Protozoa are concerned, cannot be over- 

 estimated. Lieberkuhn's observations on the development 

 of the monocystic form of the earthworm are at length suc- 

 ceeded by a knowledge of the development of a true Gre- 

 garine, with two chambers, which before was totally wanting. 



Freshwater Radiolarians. — We urgently draAV our readers' 

 attention to Mr. Archer's notices in the report of the Dublin 

 Microscopical Club in our present issue. His detection of 

 the central capsule in one of the freshw^ater Heliozoa is of 

 the greatest importance, and we are glad that so valuable a 

 piece of evidence of Radiolarian affinities has turned up. 

 Meanwhile how is it we do not hear of any of Mr. Archer's 

 beautiful forms from English localities. Will not the micro- 

 scopists of Yorkshire hunt up their moor-pools — and add to 

 our knowledge of this interesting class of forms — for the 

 discovery of Avhich science owe so much to Mr. Archer ? 

 There are moor-pools, too, in Devonshire, in Wales, in Cum- 

 berland, and in Scotland as well, which, no doubt, contain 

 further evidence of these Protozoa and new forms, such as 

 Mr. Archer's Labyrinthulean, the discovery of which must be 

 of the greatest interest. 



