58 



DESIGN IN NATURE 



PLATE XXXVU 



PLATE XXXVII (continued) 



Fig. 1 2. — Two collar-bearing, loricate monads (Salpinjfeca petiolata and Larjenmca cunpidata), x 1250 and 1500. 



Fig. 13. — Branchlet with three zooidf? of fully-developed colony-stock (Oodosiga cyinosa), x 1250. 



Fig. 14, — Free-floating colony of zooids with collars and flagella iraperl'eotly indicated, x 600 (De Fromentel). Shows radiating, 

 stellate arrangement. 



Fig. 15. — Branchlet with two zooids (Oodosiga cymosa), the one to the left (a) encysted and separated by segmentation, x 1250. 

 In this case the segmentation and division is transverse, while in Fig. 7 it is longitudinal. The longitudinal and transverse division of 

 zooids illustrates a general principle, namely, the power possessed liy living things of splitting and subdividing in various directions. 

 Longitudinal division is illustrated in the branching of plants, and in the branching of parts of animals, as in blood-vessels, bronchial 

 tubes, &c. The transverse division is seen in many plants, and obtains in articulate and vertebrate animals. 



Fig. 16. — Germ of zooid (Salpingccca ampulla) attached and developing its collar and protective lorica, x 1200. 



Figs. 17 and 18. — Zooids (Monosiga ronsociata) with collars and flagella retracted and assuming vacuolar amoeboid jjliase, x 1500. 

 Here the extraordinary power possessed by simple animals of reverting to a simple or primitive condition is strikingly manifested. 



Pig. 19. — Two adult zooids (Salpingccca miniita) and single undeveloped germ (a), attached to an empty lorica, x 1000. 



Fig. 20. — A single attached zooid (Salpingmca minuta) showing nucleus (n) and contractile vesicles (cv), x 1250. 



Fig. 21. — Free swimming zooid (Oodosiga botrytis) detached from sedentary colony, with collar contracted, x650. 



Fig. 22. — Similar zooid coalescing or conjugating with a sedentary zooid (Stein). Illustrates how zooids merge and fuse 

 into each other. 



Fig. 23. — A zooid (Salpingmca convallaria) dividing by longitudinal fission, x 650. Illustrates the dichotomous division of zooids. 

 Compare with Figs. 7 and 15 «. 



Fig. 24. — A zooid emitting minute ])seudopodio processes, x650 (Stein). These processes are produced by a voluntary pushing 

 outwards or centrifugal action of the body sarcode. They are retracted and merged in the bodj' sarcode by an opposite or centripetal 

 action. Similar powers, as indicated, are possessed by the sarcous elements of muscles, in virtue of which muscles are voluntarily 

 elongated or shortened, 



