ON DHE SMALLESE) PARTS: OF SEENTOR. CAP: 
ABLE OF REGENERATION; A CONTRIBUTION 
ON VIE, LIMITS OF DIVISIBIEITY: OF ULIVING 
MATTER. 
FRANK R. LILLIE. 
In experiments on the power of multiple development of the 
ovum the result has been reached, that a portion of less volume 
than one-fourth that of the normal ovum does not possess the 
capacity of producing an embryo or larva, though it may a 
gastrula (see postscript); while a portion equal to one-fourth or 
more of the volume of the normal ovum may, under suitable 
conditions, produce a gastrula and finally a larva of correspond- 
ing relative bulk. This result has been attained by Loeb,! 
Wilson,? Driesch,? Morgan,* and Zoja.®° Wilson found only a 
single larva of Amphioxus of one-fourth the normal size and 
that showed several defects ; and Driesch has not, so far as I 
am aware, mentioned any pluteus of less than one-quarter size. 
Morgan has recently published the results of his studies on 
the power of multiple development of the echinoderm ovum. 
In this he shows that “the volume of the smallest gastrula 
which can be produced from fragments of the egg falls below 
gz the volume of normal gastrulae. The volume of the frag- 
ments of the egg which produced such gastrulae, varies 
between ;{, and =, of the volume of the ovum.” (Summary 
q 
p. 124 loc. ct¢t.) But these smallest gastrulae were unable to 
1 Jacques Loeb. ‘On the Limits of Divisibility of Living Matter.” In Biol. 
Lectures of Marine Biol. Lab. for 1894. Boston, Ginn & Co. Also in Archiv fiir 
Ges. Physiologie von Pfliiger. Vol. LIX. 1894. 
2 E. B. Wilson. “ Amphioxus and the Mosaic Theory of Development.” 
JOURNAL OF MorpPHoLocy. Vol. VIII, No. 3. 1893. ? 
8 Driesch. “Entwicklungsmechanische Studien.” III-VI. Zeztschr. f. wiss. 
Zool. Bd. LV,p.9. 1893. 
«Studies of the Partial Larvae of Sphaerechinus,” by T. H. Morgan, in 
Roux’s Archiv fiir Entwicklungsmechanik der Organismen. Bd. Il, H. 1. 1895- 
5 Sullo sviluppo dei blastomeri isolati dalle uova di alcune meduse (e di altri 
organismi) per il Dr. Raffaello Zoja; in Roux’s Archiv fiir Entwicklungsmechanik 
der Organismen. Bd. II, H.1. 1895. 
