U56 GLOSSARY 



BAEFUTH'S EULE - when oblique cuts are made on amphibian tails, the axis of the regenerated tall will be at 

 first perpendicular to the cut surface (Barfuth, I89I). 



BATESON'S RILE - (a) The long axes of reduplicated structures lie In the same plane. 



(b) Two reduplicated limbs are mirror images of each other about a plane which bisects the 

 angle between the long axes of the members, and which Is at right angles to the plane of these axes. 



BASOPHIL - cell constituents having an affinity for basic dyes, often used as an adjective for an entire 

 cell. (See acidophil) 



BAUCHSTUCK - that portion of the amphibian gastrula (i.e., the ventral half) from which all the organizer 

 area has been removed, thus preventing the formation of any neural axis. 



BEDEUTUNGSFKEKDE SELBSTDIFFERENZIEEUNG - self-differentiation independent of the original presiimptive fate 

 or the presumed fate. Implied by the new environment. Neither selfwise nor neighborwise. 



BIDDER'S OKJAM - anterior portion of the gonad which is ovarian in character, developing from part of the 

 rudiment conaistlng wholly of cortex. A structure indicating failure of medullary substance to dif- 

 fuse to the anterior extremity of the gonad rudiment, found most frequently in male toads. 



BIO-ELECTKIC CURRENT - an electrical potential characteristic of life, disappearing upon death, associated 

 with activities of muscle, nerve, secretion, and early embryos. 



BIOGENKTIC LAW - ontogeny is a recapitulation of the early development of ancestral phylogeny. Embryos of 

 higher forms resemble the embryos of lower forms in certain respects but they are never like the 

 adults of the lower (or ancestral) forms. Not to be confused with the recapitulation theory. 



BIOLOGICAL MiMOHY - ontogenetic unfolding of anlagen phyletlcally accumulated. 



BIOLOGICAL INTEGRATION - correlation of parts through neural or humoral (or both) Influences, acquired 

 during development. 



BIOLOGICAL ORDER - fundamental basis of experimental studies, the conformity of biological processes to 

 causal postulates. 



BIOBGAN - an organ in the physiological rather than the morphological sense. 



BIOTONUS - the ratio between assimilation and dissimilation, A/D ratio (Verwom). 



BLASTEMA - an Indifferent group of cells about to be organized into definite tissues, kept together by 

 the ectoplasmic matrix of the constituent cells. Considered to be primitive, embryonic, relatively 

 undifferentiated regenerating cell masses. Thought by some to be produced by reserve cells which 

 were arrested during earlier embryonic development. 



BLASTEMFELD - unitary field-like structure (or functional state) without an anlage. Primordial fields 

 present in the egg stage, and other fields activated only by the processes of induction during 

 development (Lehmann). 



BLASTOCOEL - cavity of the blastula. Syn., segmentation or subgermlnal cavity. 



BLASTODERM - "Because the embryo chooses this as its seat and its domicile, contributing much to its 

 configuration out of its own substance, therefore, in the future, we shall call it blastoderm." 

 (Pander, I8l7). 



BLASTOKINESIS - a reversal of the cephalo-caudal axis in an egg, often accomplished by movement during 

 early development (e.g., insects). Syn., revolution. 



BLASTOMEMl - one of the cells of the early cleavage of an egg. When there is a discrepancy in size the 



smaller blaetomere is a micromere; the intermediate one is a mesomere; and the larger one is a macro- 

 mere, but all are blastomeres . 



BLASTOPORE - the opening of the archenteron (gaatrocoel) to the exterior, occluded by the yolk plug in 



amphibian embryos; consisting of a slit-like space between the elevated margin of the blastoderm and 

 the underlying yolk of the chick blastoderm; and represented In the amnlota as the primitive streak. 

 Approximate region of the future anus. 



BLASTOPORE, DOBSAL LIP OF - the region of initial Involution of cells in the amphibian or chick gastrula; 

 general area of the "organizer"; original grey crescent area of many amphibia; the cells which turn 

 in bene'ath the potential central nervous system (Amphioxus) and form the roof of the archenteron 

 (urodela). Syn., germ ring or marginal zone. 



BLASTOPORE, VENTRAL LIP OF - region of the germ ring opposite the dorsal lip after involution has reached 

 this point; region which gives rise to the peristomlal mesoderm of the frog. Syn., germ ring. 

 (Note: The lips of the blastopore are continuous and represent the involuted germ ring.) 



BLASTOTOMY - separation of cells or groups of cells of the blastula, by any means. 



BLASTULA - a stage in embryonic development between the appearance of distinct blastomeres and the end 

 of cleavage (i.e., the beginning of gastrulation) ; a stage generally possessing a primary embryonic 

 cavity or vesicle known as the blastocoel; invariably monodermlc, although the roof may be multi- 

 layered. 



BLOOD ISLANDS - pre-vaacular groups of mesodermal cells found in the spleinchnopleure, from which arise 

 the blood vessels and corpuscles. Generally extra-embryonic (chick). 



BCiTLE CELLS - long-necked, cylindrical cells of the blastoporal lips (amphibia) whose function may be 



purely morphogenetlc and related to the involutionary processes of gastrulation, (Holtfreter, 19'*5)- 

 Rufflnl (1925) showed that flask-shaped cells appear wherever Infoldings occur, as in the formation 

 of the neural tube, eye vesicle, nasal placode, atomodeum, proctodeum, etc. These cells are held 

 together by strands of surface coating. 



BBADYAUXESIS - negative heterogony ( Needham & Lemer, 19l*0), the part grows more slowly than the whole. 



BRADYGENESIS - lengthening of certain stages in development. 



BBAMCHIAL - having to do with respiration (e.g., branchial vessel In gill). 



BBAMCHlOMEHif - type of metamerism exemplified in the visceral arches. 



BEYSHTHALMIA - eyes that are too large, may be due to oversized lenses. 



BUD - an undeveloped branch, generally'an anlage of an appendage (e.g., limb or wing bud). 



BUPHTHALMIA - eyes that are .too large (Harrison, 1929)- 



