1880. | A Sketch of Comparative Embryology. 479 
needed for use as food. Not less interesting, however, would be 
instances of the use of organic refuse derived from other sources. 
Can it be possible that the agricultural Indians of America, such, 
for instance, as the Moquis, have never thought of making this 
very obvious application of their domestic animals? When did 
the Aryan races take their first steps in provident agriculture? 
These questions must be extremely important to those who are 
studying the development of culture and civilization. 
:0: 
A SKETCH OF COMPARATIVE EMBRYOLOGY, 
BY CHARLES SEDGWICK MINOT. 
IV.—THE EMBRYOLOGY OF SPONGES. 
p oeng the past six years our knowledge of the structure 
and development of sponges has made sudden añd very great 
progress, perhaps greater than has occurred in any other depart- 
ment of zodlogy during the same period. The advance was 
introduced by the publication, in 1872, of Haeckel’s monograph 
of the calcareous sponges. That work has been followed, in 
Germany, England, France and Russia, by numerous memoirs, 
among which the series of articles by Franz Eilhard Schulze 
stand first by their accuracy, their clearness, the beauty of the 
illustrations and the good temper (sometimes wanting in German 
scientific publications) of the criticisms on other investigators, 
but above all, by the value of the discoveries they announce. I 
think no zoologist can read Schulze’s papers without enjoying their 
rare combination of merits. 
One of the results of these numerous recent researches has 
been to show that Haeckel’s work is inaccurate to a startling 
extent. He figures in detail things he cannot have seen, because 
they do not exist, and he describes phenomena that do not occur. 
His fault is to'‘make very positive statements and give very dia- 
grammatic figures after a hasty examination, consequently his 
writings contain so numerous errors, sometimes about fundamen- 
tal points, that even a positive statement of his, until confirmed 
by other investigators, has no authoritative value. This defect is 
most seriously to be deplored, for Haeckel is unquestionably one 
of the most daring and original thinkers of the modern specula- 
tive school, and many of his quickly made generalizations have 
