CASE OF SARCINA VENTKICULI. 357 



yellow or Ijiuwii. "When carefully examined under favourable 

 circumstances the cell-walls appeared rj^dd, and could lie 

 perceived passing from one flat surface to the other as dis- 

 sepiments. These dissepiments, as well as the transparent 

 spaces, were from compression of contiguity rectilinear, and 

 all the angles right angles ; but the bounding cells bulged 

 somewhat irregidarly on the edges of the organism, by reason 

 of the freedom from pressure. 



These circumstances gave the whole organism the appear- 

 ance of a wool-pack, or of a soft bundle bound with cord, 

 crossmg it four times at right angles and at equal distances. 



From these very striking peculiarities of form, I propose 

 for it the generic term Saiicina.''' 



Perfect individual Sarcin.e, of the species now under 

 consideration, vary from 800 to 1000 of an inch linear 

 along each of their sides. They are, as has been stated, 

 slightly brown or yellow under a high power — under modemte 

 glasses they appear dark, and are defined with difficulty on 

 account of the frequent reflections of the light by the dis- 

 sepiments. Iodine does not react with them, as with starch, 

 but tinges them deep brown or yellow. They shrivel but 

 slightly in alcohol. In nitric acid, even after boiling for some 

 time, the sixteen ternary squares retain their relative 

 position, but diminished and shrivelled, appearing like minute 

 crj'stalline granules ari-anged in a square. So persistent are 

 those arrangements of granules in boiling nitric acid, that I 

 at one tune suspected the existence of silicious loricrr, or 

 isolated raphides, but as I could not detect the same fonns or 

 arrangements in the ashes of the evaponited and calcined fluid, 

 I do not now believe in their exi.stence. 



This species of Sarcina, therefore, consists of sixteen fo\ir- 

 celled frustules, imbedded in a square tablet of a transi>arent 



* Saucinui.a woulil hftvo bccii inorr appropriate, had in)t Iviiiiarck already 

 applied the term to a genus of polyps. 



