1879. ] Recent Literature. 693 
else to remove this reproach upon American biology. He was 
admirably adapted by nature for doing histological work, being 
cautious, careful, thorough and honest, and skillful in the techni- 
cal and mechanical part of the work. But the present memoir, 
as well as many of Clark’s other writings, evinces a thoughtful- 
ness and grasp of the subject which characterizes observers of a 
high order, though he failed at times to record his observations in 
a style as terse and simple as that of some other writers. 
Though this monograph bears as its date of publication, Sep- 
tember, 1878, five years after the author’s death, we received it in 
July of the present year. If we are to judge by the quality of 
the memoir, it is the most important zoological work (because 
involving so much hard labor and done with so much care) which 
has appeared in this country for several years, and we say this 
without disparagement to others. 
e Lucernaria is a creature, not often met with, living attached 
by its tail or peduncle to eel grass or sea weeds just beyond low- 
water mark. The differences of opinion regarding its true posi- 
tion in nature, whether to be reckoned a jelly-fish or a type of a 
distinct order, led the author, who had paid so much attention to 
the Polyps and Acalephs, to devote time extending over several 
years to the full elaboration of its general and minute anatomy, 
its mode of development and relations to neighboring types of 
life. This has led to the preparation of an elaborate monograph, 
most carefully prepared, and illustrated by drawings which are 
not inferior in faithfulness, finish and artistic effect to those of any 
American, and few European delineators of the invertebrate.ani- 
mals. The text is divided into seven chapters; in the first, on 
individuality, the author discusses the subject of animal individ- 
uality, illustrating his points by reference mainly to the polyps 
and acalephs. The subject is sufficiently simple when the verte- 
brates are involved, but among the polyps, jelly-fishes, Polyzoa 
and Ascidians, where many forms are social, compound and often 
many-headed, it is difficult to say where the organ ends and the 
individual begins. The author clearly distinguishes between 
organs like those of the Tubularians and Siphonophores which 
have a high degree of individuality, and the individual joints (pro- 
glottides) of the tape worms; and does not fall into the error o 
regarding the former as truly individuals. The sexual and sexless 
organs of the polycephalic Acalephs, such as the Tubularians, 
‘are necessary to make up a complete organism, 2. e., vegetative 
and reproductive, the one a complement of the other, neither 
alone can represent the individual unit, or whole cycle of life.” We 
infer from the statement made that Clark regarded the so-called 
polymorphic individuals as “ organs under various disguises ;” a 
view which seems to us most reasonable. Clark ascribes a high 
degree of individuality to the jelly-fish, Pelagia, and only a less 
_ amount to Lucernaria. 
