QUARTERLY CHRONICLE OF MICROSCOPICAL 
SCIENCE. 
Conjugations of Navicula serians, N. rhomboides, and 
Primularia gibba. By H.T. Carrzur, F.R.S. (‘Ann. and Mag. 
of Nat. Hist.,’ March, 1865.)—This is a most valuable and 
remarkable paper, and one which cannot fail to attract much 
attention from microscopists, more particularly those who 
are engaged in the investigation of the Diatomacer. Only 
thirty-two species of the Diatomacez are recorded as having 
been seen ina state of conjugation, and nine years ago, when 
Mr. Carter published his descriptions of three species under- 
going that process, twenty had been observed, so that no 
great progress bas been made in this branch of inquiry. Mr. 
Carter returns to it now, having been anxious, he states, to sa- 
tisfy himself of the presence of a transversely ringed siliceous 
sheath enclosing the sporangial frustule, which was observed 
by Dr. Griffith, in a Navicula form. Huis observations have 
been made on the three species above-named, obtained from 
bogs in the neighbourhood of Budleigh Salterton, in Devon- 
shire, and enveloped ina gelatinous mass. We extract his de- 
scription of the conjugation in Navicula serians, Rg.:—“1. 
Two frustules, varying a little more or less in size, approximate 
themselves. 2. They secrete a gelatinous substance around 
them, which becomes covered by a delicate pellicular mem- 
brane. 38. The sarcodal sacs force open respectively their 
frustules through the fissiparating divisional line, and carrying 
with them their contents, now all undistinguishably mixed 
together, approach each other and unite into one (?) sphe- 
rical mass called the spore or sporangium. 4. The sporan- 
gium divides itself equally into two spherical sporangial cells, 
each of which forms around itself a thick opalescent capsule. 
5. The capsules respectively divide in their equatorial lines, 
and expose the sheaths of the sporangial frustules. 6. The 
sheaths become elongated, and at the same time present 
thread-like rings on their surface, diminishing gradually in 
thickness towards each extremity, but in close approxima- 
