38 PROGRESS OF MICROSCOPICAL SCIENCE. 
by means of a series of new cells. All experiments prove the life of 
the spore to be very short, but when the spore once germinates and 
forms spawn the latter material’ has great tenacity of life, and this 
mycelium is commonly, if not always, perennial.” 
American Work with the Microscope.—We have been furnished by 
Mr. A. 8. Packard with a valuable sketch of the work that has been 
done with the microscope in America. This, however, has only to do 
with zoological progress; and great though it undoubtedly is, we 
cannot agree with the author in his assertion* that it is vastly superior 
to the labours during the same time of those who worked at the same 
subjects in either France or England. The following is part of Mr. 
Packard’s paper, which includes all the American labours in zoology :— 
“The epoch of embryology or the developmental study of animals 
was inaugurated by Agassiz in 1846. In the publication of his 
‘Contributions to the Natural History of the United States, mainly 
devoted to the developmental history of the radiates and turtles, 
Agassiz was assisted by H. J. Clark, who, under his training, became 
the best histologist our country has yet produced. W. J. Burnett, 
another histologist, was only inferior to Clark. Macrady, another of 
Agassiz’s students, published some papers of importance on the 
Acalephs and their mode of development. Desor and Girard wrote 
on the embryology of worms. Memoirs of a high order of merit fol- 
lowed, from the pen and pencil of Mr. Alexander Agassiz. His 
embryology of the Echinoderms appeared between 1864 and 1874; 
the memoir on the alternation of generations of the worm, Autolycus, 
appeared in 1862; his paper on the early stages of Annelids in 
1866; his remarkable memoir on the transformation of Tornaria 
into Balanoglossus was published in 18783; and his elaborate 
embryology of the Ctenophores in 1874. In 1864, Jeffries Wyman, 
at the time of his death our leading American comparative anatomist 
and physiologist, published a memoir on the development of the skate. 
The beautiful memoir of Hyatt on the embryology of Ammonites was 
a difficult research, while the brilliant papers of Morse on the early . 
stages of the Brachiopod, Terebratulina, published in 1869-73, enabled 
him, by embryological as well as anatomical evidence, to transfer the 
Brachiopods from the Mollusca to the vicinity of the Annelidan 
worms. His studies on the carpus and tarsus of embryo birds should 
also be mentioned. In 1872 Packard published a memoir on the 
development of Limulus, and pointed out the affinities of its young to 
certain young Trilobites; and he also published papers on the embry- 
ology of the Thysanourous, Neuropterous, Coleopterous, and Hymenop- 
terous insects. 8. I. Smith traced the metamorphoses of certain crabs 
and shrimps. Several entomologists, as Harris, L. Agassiz, Fitch, 
Riley, Scudder, Packard, LeBaron, Hagen, Cabot, Walsh, Saunders, 
Edwards, and others, have studied the metamorphoses of insects, 
while the drawings in illustration of Abbot and Smith’s ‘ Natural 
History of the Rarer Insects of Georgia’ were made by Abbot, who 
lived several years in Georgia. In 1874 Emerton described the 
embryology of the spider, Pholcus, and during the present year an 
American Naturalist,’ October. 
