ZOOLOGY AND BOTANY, MICROSCOPY, ETC. o43 



of sodium, and half a gramme of pure bicLloride of mercury, the blood- 

 corpuscles are separately isolated and distinguished from the other 

 constituents. The fibrine then breaks up into two distinct groups. 



Perfectly normal blood, thus treated, shows the following reactions : 

 At the moment when it coagulates it is traversed by a very delicate 

 network of filaments. If at the moment of coagulation a reticulum 

 of thick fibrillee is seen, we may be sure that we have indications 

 of an inflammatory lesion, and the modifications in the processes of 

 coagulation are due to the extent and intensity of the inflammation. 

 Pyrexia is not accompanied by any appreciable modification of the 

 fibrine ; but when fevers are complicated by inflammatory processes 

 there are such modifications. In small-pox they only appear with 

 the suppurating fever ; in scarlet-fever and scarlatina the fibrine only 

 augments at the period of desquamation. So again, in typhoid and 

 intermittent fevers the so-called phlegmatic characters only appear 

 when the disease is comj^licated by inflammation. 



When cachectic conditions are not the results of chronic diseases, 

 which bring about inflammatory lesions, the reticulum of the puro 

 blood generally remains invisible, or is obscure, notwithstanding the 

 unusual abundance of htematoblasts. Examination by the aid of the 

 solution already described, shows, however, that the fibrine is allied ; 

 in advanced cases one often observes the so-called " plaques cachec- 

 tiques," due to the infiltration of the heematoblasts by a finely granular 

 substance, which points to a qualitative change in the characters of 

 the fibrine. 



Diatoms as Test Objects.* — L. Dippel publishes the result of 

 observations on the value of certain diatoms as test objects for the Micro- 

 scope, accompanied by exact measurements of the number of strife. 



The various forms of Navicula rliomboides are first discussed. The 

 largest forms, called by the author var. Leicisiana (but quite distinct from 

 the true and very interesting N. Leicisiana) has from 22 to 24 trans- 

 verse strife in 0* 01 mm. ; the ordinary N. rliomboides has 28 to 30 ; and 

 the var, saxonica {N. crassinervia Breb.) from 33 to 35 in O'Ol mm. 



The true Grammatopliora suhtilissima Bailey occurs but rarely as a 

 test object, and has 34-36 transverse strife per O'Ol mm. G. rnaci- 

 lenta W. Sm., which is usually supplied for it, has 25-28 ; G. oceanica 

 Ehbg. 21-22; and G. marina 14-16 per O'Ol mm. The author 

 describes G. islandica Ehbg. with 10-12 ; G. serpentina, with 17-18 

 transverse strife per • 01 mm. ; the double structure of G. gihhenda ; 

 and G. robiista Dippel, a new species with 14-16 transverse strife per 

 0*01 mm. G. tropica Kg., to which G. marina Dippel also belongs, 

 has 13 '5-15 '5 transverse striae per O'Ol mm.; the true G. marina 

 Lyngbye has 20-5-21. G. marina W. Sm. is one of the numerous 

 intermediate forms between G. tropica Kg. and G. marina Lyngbye. 



Nitzschia curvula has 35 36, N. sigmatella 26, and N. sigma 20-22 

 transverse strife per 0*01 mm. 



Drawings are given of all the forms described. It may be stated 

 that all the drawings in Kiitzing's ' Bacillarx-fe ' are magnified only 

 from 255 to 260, and not, as stated, 420 times. 



* Zeitschr. f. MikroskopL , ii. (1.^80) (4 pis.). 



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