82 NOTES AND COMMENTS [august 



A Rare Rotifer. 



In October 1859 Professor Semper discovered in some ditches inter- 

 secting rice -fields in the Philippine Islands a remarkable spherical 

 rotifer, which he named TrocJiosphaera aequatorialis, in allusion to the 

 ciliary wreath which divides it into two hemispheres. For thirty years 

 nothing more was seen of the creature, until Surgeon Gunson Thorpe found 

 it (1889) in Pern Island pond of the Botanical Gardens at Brisbane. 

 In 1892 he discovered in some irrigation creeks and ponds near 

 Wuhu on the Yangtsze Kiang a new species (T. solstitialis) in which 

 the ciliary wreath encircles the body as the Tropic of Cancer does the 

 earth. In 1896 the same species was found in the Illinois Eiver by 

 Dr. C. A. Kofoid, and in 1898 by Mr. H. S. Jennings, in a pond close 

 to Lake Erie. We have taken this information from a short note by 

 Mr. C. F. Ptousselet (Journ. Quekett Micr. Club, vii. (1899) pp. 190-193, 

 1 fig.) who recently exhibited to the Quekett Club a slide of T. solsti- 

 tialis, prepared according to his method by Mr. Jennings. This was 

 the first time the animal had been seen in the flesh in England. " The 

 anatomy is extremely simple and beautifully displayed, all the organs, 

 usually so indistinct and closely packed together in rotifers, being here 

 spread out and suspended in the transparent sphere in the most delight- 

 ful manner." It is said that Dr. Kofoid is preparing a full account 

 of this remarkable type. 



Does the Organism Repeat Itself? 



In an interesting paper entitled " Localised Stages in Development in 

 Plants and Animals " (Mem. Boston Soc. Nat. Hist. v. (1899) pp. 89-153, 

 10 pis.), Mr. Eobert Tracey Jackson elaborates an interpretation which 

 is in direct line with the ideas expressed by Hyatt, Cope, Eyder, 

 Beecher, and some other American workers. It is especially in harmony 

 with Hyatt's law of senile characters : — ■" In the old age, stages are 

 found which are similar to stages found in the young, and are prophetic 

 of types to be found in degradational series of the group to which the 

 animal belongs." But Mr. Jackson's particular point is that in addition 

 to stages in the young and in the old age, stages may be found in 

 localised parts throughout the life of the organism. 



" In organisms that grow by a serial repetition of parts, it is found 

 that there is often an ontogenesis of such parts which is more or less 

 closely parallel to the ontogenesis of the organism as a whole. In the 

 ontogeny of such localised parts in a mature individual we find stages 

 in development during the growth of the said parts which repeat the 

 characters seen in a similar part in the young individual." 



Such localised stages have been observed in the leaves of plants, in 

 branches or suckers of plants, in the budding of some of the lower 



