176 



THE AMERICj\N MONTHLY 



[September, 



The under glass is moved up and 

 down by means of a convenient 

 screw, while the cover remains sta- 

 tionary, and the motion is very 

 smooth. A good compressorium is 

 of great value to the general micro- 

 scopist. Americans have not yet 

 come to appreciate it ; by its use, 

 many points of structure can be easi- 

 ly demonstrated without resorting to 

 delicate and tedious dissections. The 

 price of this instrument is only $4.00. 



The Boring Sponge. — The July 

 number of the Journal of the Quekett 

 Club contains three articles upon 

 sponges, which possess considerable 

 interest. The first is by B. W. Priest, 

 " On the Natural History and His- 

 tology of Sponges," but the second 

 article " On Cliona celata — Does the 

 Sponge make the Burrow ? " by J. G. 

 Waller, and the last one, by Mr. 

 Priest, in which the same subject is 

 considered, are deserving of special 

 notice. In the opinion of Mr. Wal- 

 ler, the sponge is not capable of bor- 

 ing or excavating in limestone-rock 

 or shells, either by a mechanical pro- 

 cess of abrasion or by chemical ac- 

 tion, and he believes that the bur- 

 rows inhabited by the sponge are all 

 produced by the boring of some an- 

 nelid, regarding the sponge as para- 

 sitic. By microscopical examination 

 he traces a similarity between the ex- 

 cavations inhabited by the sponge, 

 and others which are unquestionably 

 produced by annelids boring with a 

 hard tool working in in the segment 

 of a circle, as the larva of Scolytus, 

 for example. The parasitic nature of 

 the sponge is indicated by its habitat 

 in deserted polypedoms of Polyzoa, 

 the tubes of Scopulse, etc. Mr. Priest 

 holds to the opposite opinion, al- 

 though admitting that it is still a 

 problem how the sponge can pene- 

 trate solid limestone-rock. He was 

 at one time inclined to the belief that 

 the boring was done by other organ- 

 isms, but after a more careful study 

 of the subject, he found cavities 



" which ramified right and left into 

 such fine processes, and those cavi- 

 ties being filled with the sponge," he 

 finally concluded that no annelid 

 could produce such work. The whole 

 question is left in a state of uncer- 

 tainty ; and we are inclined to ask, if 

 the boring sponge is misnamed be- 

 cause it cannot perforate hard sub- 

 stances, what is the nature of the 

 magnanimous creature that prepares 

 its dwelling places ? 



FiLARiA IN THE Blood. — An in- 

 teresting letter from P. Manson, M. D., 

 who has been studying the filariae in 

 the blood of two Chinese lads, to Dr. 

 T. Spencer Cobbold, is printed in the 

 Journal of the Quekett Club for July. 

 The filariae are long, hair-like worms 

 belonging to the Entozoa. They are 

 found in the blood of persons who 

 may apparently enjoy good health at 

 the time. They seem to occur quite 

 frequently in China. A most myste- 

 rious phenomenon connected with 

 these organisms is their periodicity. 

 Between four and six o'clock in the 

 afternoon the filariae begin to appear 

 in the blood, their number increases 

 until midnight and then diminishes 

 until nine or ten o'clock in the morn- 

 ing, when they have entirely disap- 

 peared. This daily periodical recur- 

 rence of the worms seems to be quite 

 independent of the habits of the pa- 

 tient, and has not yet been explained. 



The Micrographic Dictionary. 

 — The first two parts of the fourth 

 edition of this valuable publication, 

 which, as announced in these col- 

 umns last month, is to be published 

 in monthly parts, have been issued. 



The work begins with the " Intro- 

 duction," which is somewhat longer 

 than and different from that of pre- 

 vious editions. Owing to the pecu- 

 liar nature of the book we cannot 

 attempt to notice the contents in a 

 specific manner ; but looking over 

 the pages we find evidences of the 



