340 



SCIENCE. 



[N. S. Vol. XI. No. 270. 



that the Laboratory has won greatest re- 

 nown. The eminent scientific standing of 

 the Director and his co-laborers has served 

 to attract investigators from all parts of the 

 land, until the Woods Holl Laboratory is 

 to-day the Mecca of American biologists 

 and is well and favorably known through- 

 out the world. The list of original con- 

 tributions which have proceeded from the 

 Laboratory during the past twelve years 

 numbers _about three hundred; many of 

 these are large monographs, illustrated 

 with numerous colored plates, and some of 

 them represent unique lines of research. 

 For example, the study of ' cell-lineage,' 

 as it has been called, had its origin at the 

 Woods Holl Laboratory and has so far been 

 confined almost entirely to that institution. 

 This work consists in tracing the cleavage 

 cells, into which the developing eggs of all 

 animals divide, through the whole develop- 

 ment until they give rise to larval or adult 

 organs, such as the brain, nerves, sense or- 

 gans, glands, alimentary canal, etc. This 

 is in all cases a diflScult task, frequently 

 taking years of the most painstaking labor, 

 but its results have been of fundamental 

 and far reaching importance. Thanks to 

 this work we now know the cell-lineage of 

 about a score of worms and moUusks. 

 This work has shown that from their first 

 appearance certain cleavage cells are des- 

 tined to give rise to certain organs ; it has 

 shown that, in the groups mentioned, cleav- 

 age is as constant in its character as are 

 adult features ; that in animals so widely 

 separated as flat- worms, annelids and mol- 

 lusks these early divisions of the egg are 

 almost identical and that many correspond- 

 ing cleavage cells give rise to homologous 

 organs. Incidentally such work has shown 

 the close genetic relationship of the groups 

 named ; it has also set a new pace in em- 

 bryology. Now that we know the exact 

 cell origin of these layers and organs, it 

 will never again be possible in describing 



the development of these animals to refer 

 the origin of certain organs to ' germ layers ' 

 merely, nor to refer the origin of these lay- 

 ers to certain general regions of the embryo. 

 The importance of this line of work, not 

 only in the study of the groups named, but 

 also to the science of embrj'ology as a whole, 

 is fully recognized both in this country and 

 abroad, and the credit for this service be- 

 longs in large part to the Woods Holl Lab- 

 oratory. 



Other work of the greatest importance 

 has been done in the line of what has 

 been called ' physiological morphology.' It 

 would exceed the limits of this article to 

 give even a brief description of papers of 

 this class which have issued from the Lab- 

 oratory. A few of the more striking lines 

 of work, however, must be mentioned. 

 Much attention has been given to experi- 

 ments on the regeneration of lost parts in 

 various animals. In hydroids, sea-anem- 

 ones and worms these parts are some- 

 times reproduced in a normal manner, 

 while under different conditions a head 

 may be caused to develop where a tail be- 

 longs or vice versa. Another line of work 

 has been the grafting together of different 

 parts of animals. One member of the Lab- 

 oratory succeeded in grafting together in 

 almost every possible manner the pupse of 

 different moths and butterflies. Some of 

 these afterwards went through the meta- 

 morphosis and came out as ' Siamese twins,' 

 ' tandems ' with four wings, etc. Another 

 line of work, even more important, is found 

 in ' experimental embryology.' In one fa- 

 mous experiment performed at the Labora- 

 tory, the eggs of the sea-urchin were arti- 

 ficially fragmented before they began their 

 development, and in this way twins, trip- 

 lets, or still more numerous larvte might be 

 produced from a single egg. If the frag- 

 ments of the egg were entirely separate, the 

 larvse which developed were separate and 

 perfect, if they were united, the larvse were 



