xli 



detection in 1863 in a small rock-pool, no larger than a wash-hand 

 basin, on Bray Head, of the beautiful Volvocinacea, Stephanospha>ra 

 pltwialis, Cohn, then only known from six isolated localities ranging 

 from Scotland to Austria. He described for the first time an 

 amoeboid state of the constituent cells. 



When the writer of this notice went to reside in Ireland in 1870, 

 the parting advice of a friend was to seek out and make the acquaint- 

 ance of Archer. Under his guidance the treasures were revealed of 

 a field of nature as fascinating as it was novel. Nothing can 

 be imagined more entrancing than the work under Archer's guid- 

 ance of examining with the microscope the results of a day's 

 gatherings. 



In the course of the long period which Archer devoted to their 

 study he acquired a knowledge of the minute fresh- water organisms 

 of Ireland which was certainly unequalled amongst British naturalists, 

 and perhaps not surpassed for any other country. But he did not 

 content himself with the mere identification and cataloguing of forms. 

 He was constantly observant of their biological significance, and to 

 follow the work of others in this respect, he made himself acquainted 

 with the principal- European, and especially Scandinavian languages. 

 The chief of his detailed observations were communicated to the 

 Dublin Microscopical Club, and are to be found in its minutes, which 

 from 1864 were published in the ' Quarterly Journal of Microscopical 

 Science.' 



More extended studies were given in a series of separate papers 

 published in various scientific journals. Of these the titles of fifty- 

 nine are contained in the Ttoyal Society's ' Catalogue.' He was 

 fastidious in recording anything which he had not worked out to his 

 complete satisfaction, and much of the results of his laborious re- 

 search is doubtless lost. His most considerable contribution to 

 algology is the revision of the Destuideae in the second edition of 

 Prit chard's ' Infusoria.' 



It is, however, probably to his work amongst the Protozoa that 

 Archer will owe his ultimate place in science. It was his good 

 fortune to discover in 1868 Chlamydomyxa labyrinthuloicles, one of the 

 most remarkable and enigmatical of all known microscopic organ- 

 isms. In 1867 Cienkowski had described, from the harbour of Odessa, 

 Labyrinthula, the only other with which Chlamydomyxa can be com- 

 pared. The two together form Lankester's class Labyrinth ulidea ; 

 but, though both produce a protoplasmic network, Chlamydomyxa, 

 unlike Labyrinthula, possesses a laminated cellulose shell, within 

 which it is most usually found inclosed. As Lankester points out, it 

 has obvious affinities with the Mycetozoa, but its ultimate place in 

 classification is a problem which still awaits the result of further in- 

 vestigation. Archer's admirable research, the result of many years 



