24: 



THE AMERICAN MONTHLY 



[February, 



which measure about 105 degrees. 

 Pure tallow appears in long curved 

 crystals, single or in groups. The 

 crystals should be obtained by evapo- 

 ration in the tube without heat, not 

 by evaporation on the slide. Ten per 

 cent, of tallow in lard can thus be de- 

 tected, and probably five per cent. 

 The addition of 15 per cent, of lard to 

 tallow was also detected by this method 

 by Dr. Lester Curtis, without expe- 

 rience with the method. It is prob- 

 able that an experienced observer 

 could detect a still smaller proportion 

 with certainty. 



o- 



A New Infusoriaii Belonging to 

 the Grenus Pyxicola. 



BY DR. ALFRED C. STOKES. 



The loricate infusorium represented 

 in fig. 5, magnified 450 diameters, ap- 

 pears to be 

 un describ- 

 ed ; but on 

 account of 

 the difficul- 

 ty a student 

 has of keep- 

 ing even par- 

 ti ally in- 

 formed of 

 the progress 

 of investiga- 

 tion among 

 the lower 

 f o r m s of 

 animal life, 

 the writer 

 names it 

 jPy xi cola 

 constr icta 

 provisional- 

 ly. As the 

 animalcule 

 is probably 

 not uncom- 

 m o n , al- 

 though I 

 have thus far 

 found it in but one locality, it may 

 easily have been described in the re- 

 cent past and the publication have 

 failed to come to my notice. 



5. — Pyxicola constricta, 

 n. sp. X 450. 



Theurceolate lorica, slightly curved 

 and gibbously inflated, is widest cen- 

 trally, whence it gradually diminishes 

 in diameter anteriorly, to the origin 

 of the produced, truncate, obliquely 

 set neck, immediately behind which 

 it is somewhat constricted, and pos- 

 teriorly to the truncate area of inser- 

 tion of the short pedicel, above which, 

 at a distance almost equalling the 

 pedicel in height, it is again con- 

 stricted thus forming a distinct pos- 

 terior prolongation ; the outline of the 

 lorica, as seen in optical section, is 

 more or less irregularly undulate ; 

 height about two and one-fourth times 

 the width ; it varies with age, as usual, 

 from colorless and hyaline to a semi- 

 opaque chestnut-brown. 



Pedicel one-twelfth the height of 

 the lorica, finely striate or wrinkled 

 lengthwise, permanently transparent, 

 but at the point of attachment to the 

 water-weed surrounded by a broad, 

 irregularly outlined annulus, which 

 varies in color with the lorica and is 

 often found adherent to the plant after 

 the entire infusorium has disappeared. 



Enclosed animal colorless ; when 

 expanded subcylindrical, slightly ta- 

 pering posteriorly and attached to the 

 lorica through the intermedium of a 

 short, thick, longitudinally and finely 

 striate foot-stalk ; when fully extend- 

 ed, about one-fifth of its entire length 

 protrudes beyond the aperture ; other- 

 wise it does not apparently differ from 

 the other animals of the genus. 



The operculum is conspicuous in 

 the older individuals only, and when 

 retracted completely occludes the ori- 

 fice at the point of constriction of that 

 part of the lorica which is obliquely 

 produced to form the neck. It is 

 disk-shaped and changes in color vv^ith 

 the lorica. 



The systole of the pulsating vesicle 

 takes place once in thirty seconds. 



Height of the lorica -g^-g^-inch. 



One method of reproduction is by 

 the formation of a lateral bud and its 

 subsequent separation as a ciliated 

 germ, w^hose complete development I 

 have not been able to follow. 



